Re-enable previously flaky BPF tests now that QEMU is in use (#1339)

Summary: Re-enable previously flaky BPF tests now that QEMU is in use

The investigations on #699 and
#700 show this was a concurrency
/ bcc / kernel issue. Future test builds should show more stable test
runs now that our test runner provides an isolated kernel for each BPF
test via qemu.

Relevant Issues: #699 #700

Type of change: /kind test-infra

Test Plan: Updated `--runs_per_test` to 30 and verified that the tests
were stable (see earlier commits in this PR for the details):
- [x] 6.1 Kernel build had 100% pass rate for
`stirling_wrapper_container_bpf_test` and ~98% pass rate for
`openssl_trace_bpf_test` ([buildbuddy
link](https://bb.px.dev/invocation/771c30f4-592e-4e05-a792-cb838280c95f#))
```
//src/stirling/e2e_tests:stirling_wrapper_container_bpf_test             PASSED in 56.7s
  Stats over 30 runs: max = 56.7s, min = 50.2s, avg = 54.3s, dev = 2.0s
//src/stirling/source_connectors/socket_tracer:openssl_trace_bpf_test     FLAKY, failed in 1 out of 61 in 1801.4s
  Stats over 61 runs: max = 1801.4s, min = 326.8s, avg = 395.0s, dev = 183.1s
```
- [x] 4.14 Kernel build had 100% pass rate for
`stirling_wrapper_container_bpf_test` and `openssl_trace_bpf_test` 100%
([buildbuddy
link](https://bb.px.dev/invocation/5b7fd005-26e4-43c8-9cda-4aa9e836e35c))
```
//src/stirling/e2e_tests:stirling_wrapper_container_bpf_test             PASSED in 121.0s
  Stats over 30 runs: max = 121.0s, min = 110.8s, avg = 114.0s, dev = 2.7s
//src/stirling/source_connectors/socket_tracer:openssl_trace_bpf_test    PASSED in 819.7s
  Stats over 60 runs: max = 819.7s, min = 656.2s, avg = 728.2s, dev = 36.4s
```

The GitHub action for the 4.14 kernel is running slowly. I'll update
this comment when I have the results, but I think the successful 6.1
build mentioned above validates the test stability.

---------

Signed-off-by: Dom Del Nano <ddelnano@pixielabs.ai>

Author: ddelnano

src/stirling/e2e_tests/BUILD.bazel

@@ -149,8 +149,6 @@ pl_sh_bpf_test(
     ],
     flaky = True,
     tags = [
-        # TODO: This test has a <90% pass rate in CI, please fix and re-enable.
-        "disabled_flaky_test",
         "requires_bpf",
         "cpu:16",
         # Run exclusive, otherwise BPF probe cleaner may conflict with open probes of other instances,

src/stirling/source_connectors/socket_tracer/BUILD.bazel

@@ -437,8 +437,6 @@ pl_cc_bpf_test(
     flaky = True,
     shard_count = 2,
     tags = [
-        # TODO: This test has a <90% pass rate in CI, please fix and re-enable.
-        "disabled_flaky_test",
         "cpu:16",
         "no_asan",
         "requires_bpf",