sp_BlitzIndex: remove inner version gate that blocked Azure SQL DB

The in-procedure version check (ProductVersion <= 12) would block
Azure SQL DB which reports major version 12.x. The pre-procedure
gate already enforces the minimum version while allowing Azure
(EngineEdition 5/6/8), matching the sp_Blitz pattern.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: BrentOzar

sp_BlitzIndex.sql

@@ -1466,16 +1466,6 @@ BEGIN TRY
         DECLARE @d VARCHAR(19) = CONVERT(VARCHAR(19), GETDATE(), 121);
         RAISERROR (N'starting at %s',0,1, @d) WITH NOWAIT;
 
-        --Validate SQL Server Version
-
-        IF (SELECT LEFT(@SQLServerProductVersion,
-              CHARINDEX('.',@SQLServerProductVersion,0)-1
-              )) <= 12
-        BEGIN
-            SET @msg=N'sp_BlitzIndex is only supported on SQL Server 2016 and higher. The version of this instance is: ' + @SQLServerProductVersion;
-            RAISERROR(@msg,16,1);
-        END;
-
         --Short circuit here if database name does not exist.
         IF @DatabaseName IS NULL OR @DatabaseID IS NULL
         BEGIN