Improve ExternalSorter ResourcesExhausted Error Message (#20226)

## Which issue does this PR close?

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- Closes #20225.

## Rationale for this change

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## What changes are included in this PR?
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When there is not enough memory to continue external sort, either
increasing the `memory limit` or decreasing
`sort_spill_reservation_bytes` need to be applied. It can be useful to
guide the user with clearer error message by highlighting required
configs for the consistency because expected settings are as follows:
```
SET datafusion.runtime.memory_limit = '10G'
SET datafusion.execution.sort_spill_reservation_bytes = 10485760
```
Current:
```
Not enough memory to continue external sort. Consider increasing the memory limit, 
or decreasing sort_spill_reservation_bytes
```
New:
```
Not enough memory to continue external sort. Consider increasing the memory limit config: 
'datafusion.runtime.memory_limit', or decreasing the config: 'datafusion.execution.sort_spill_reservation_bytes'.
```

## Are these changes tested?
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A new UT case has been added to cover this use-case and it has been
tested locally successfully.

**For updated snapshot files:**
Following integration tests have been successful by DataFusion Test
Pipeline:
```
test test_cli_top_memory_consumers::case_1 ... ok
test test_cli_top_memory_consumers::case_2 ... ok
test test_cli_top_memory_consumers::case_3 ... ok
```
**Ref:**
https://github.com/apache/datafusion/actions/runs/21811797863/job/62925363536?pr=20226

## Are there any user-facing changes?
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updated before approving the PR.
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Yes, improving legacy `ExternalSorter` `ResourcesExhausted` Error
Message.

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change` label.
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Author: erenavsarogullari

datafusion-cli/tests/snapshots/cli_top_memory_consumers@no_track.snap

@@ -14,7 +14,7 @@ success: false
 exit_code: 1
 ----- stdout -----
 [CLI_VERSION]
-Error: Not enough memory to continue external sort. Consider increasing the memory limit, or decreasing sort_spill_reservation_bytes
+Error: Not enough memory to continue external sort. Consider increasing the memory limit config: 'datafusion.runtime.memory_limit', or decreasing the config: 'datafusion.execution.sort_spill_reservation_bytes'.
 caused by
 Resources exhausted: Failed to allocate
 

datafusion-cli/tests/snapshots/cli_top_memory_consumers@top2.snap

@@ -14,7 +14,7 @@ success: false
 exit_code: 1
 ----- stdout -----
 [CLI_VERSION]
-Error: Not enough memory to continue external sort. Consider increasing the memory limit, or decreasing sort_spill_reservation_bytes
+Error: Not enough memory to continue external sort. Consider increasing the memory limit config: 'datafusion.runtime.memory_limit', or decreasing the config: 'datafusion.execution.sort_spill_reservation_bytes'.
 caused by
 Resources exhausted: Additional allocation failed for ExternalSorter[0] with top memory consumers (across reservations) as:
   Consumer(can spill: bool) consumed XB, peak XB,

datafusion-cli/tests/snapshots/cli_top_memory_consumers@top3_default.snap

@@ -12,7 +12,7 @@ success: false
 exit_code: 1
 ----- stdout -----
 [CLI_VERSION]
-Error: Not enough memory to continue external sort. Consider increasing the memory limit, or decreasing sort_spill_reservation_bytes
+Error: Not enough memory to continue external sort. Consider increasing the memory limit config: 'datafusion.runtime.memory_limit', or decreasing the config: 'datafusion.execution.sort_spill_reservation_bytes'.
 caused by
 Resources exhausted: Additional allocation failed for ExternalSorter[0] with top memory consumers (across reservations) as:
   Consumer(can spill: bool) consumed XB, peak XB,

datafusion-examples/examples/execution_monitoring/memory_pool_tracking.rs

@@ -110,7 +110,8 @@ async fn automatic_usage_example() -> Result<()> {
             println!("✓ Expected memory limit error during data processing:");
             println!("Error: {e}");
             /* Example error message:
-                Error: Not enough memory to continue external sort. Consider increasing the memory limit, or decreasing sort_spill_reservation_bytes
+                Error: Not enough memory to continue external sort. Consider increasing the memory limit config: 'datafusion.runtime.memory_limit',
+                or decreasing the config: 'datafusion.execution.sort_spill_reservation_bytes'.
                 caused by
                     Resources exhausted: Additional allocation failed with top memory consumers (across reservations) as:
                     ExternalSorterMerge[3]#112(can spill: false) consumed 10.0 MB, peak 10.0 MB,

datafusion/physical-plan/src/sorts/sort.rs

@@ -819,7 +819,8 @@ impl ExternalSorter {
         match e {
             DataFusionError::ResourcesExhausted(_) => e.context(
                 "Not enough memory to continue external sort. \
-                    Consider increasing the memory limit, or decreasing sort_spill_reservation_bytes"
+                    Consider increasing the memory limit config: 'datafusion.runtime.memory_limit', \
+                    or decreasing the config: 'datafusion.execution.sort_spill_reservation_bytes'."
             ),
             // This is not an OOM error, so just return it as is.
             _ => e,
@@ -1736,6 +1737,21 @@ mod tests {
             "Assertion failed: expected a ResourcesExhausted error, but got: {err:?}"
         );
 
+        // Verify external sorter error message when resource is exhausted
+        let config_vector = vec![
+            "datafusion.runtime.memory_limit",
+            "datafusion.execution.sort_spill_reservation_bytes",
+        ];
+        let error_message = err.message().to_string();
+        for config in config_vector.into_iter() {
+            assert!(
+                error_message.as_str().contains(config),
+                "Config: '{}' should be contained in error message: {}.",
+                config,
+                error_message.as_str()
+            );
+        }
+
         Ok(())
     }
 
@@ -1756,7 +1772,7 @@ mod tests {
 
         // The input has 200 partitions, each partition has a batch containing 100 rows.
         // Each row has a single Utf8 column, the Utf8 string values are roughly 42 bytes.
-        // The total size of the input is roughly 8.4 KB.
+        // The total size of the input is roughly 820 KB.
         let input = test::scan_partitioned_utf8(200);
         let schema = input.schema();