[#30367] YSQL: Log before invalidating table cache after ALTER TABLE

Summary:
When a transaction executes an ALTER TABLE operation, we remember the table id in ddl_transaction_state.altered_table_ids and upon COMMIT, we
invalidate the table cache of such tables.

We are investigating a "schema version mismatch" error (linked bug) which executes an ALTER TABLE post TRUNCATE. Add log to aid the investigation.
Note that since DDLs are not that frequent, this log can be at INFO level.

Test Plan:
Jenkins: compile only

Just adds a log, so no need to run the tests. I've run the transactional ddl test locally.

Reviewers: myang, fizaa

Reviewed By: fizaa

Subscribers: yql

Differential Revision: https://phorge.dev.yugabyte.com/D50670

Author: dr0pdb

src/postgres/src/backend/utils/misc/pg_yb_utils.c

@@ -4507,6 +4507,9 @@ YbInvalidateTableCacheForAlteredTables()
 			YbDatabaseAndRelfileNodeOid *object_id =
 				(YbDatabaseAndRelfileNodeOid *) lfirst(lc);
 
+			YBC_LOG_INFO("Invalidating table cache entry for table %u:%u",
+						 object_id->database_oid, object_id->relfilenode_id);
+
 			/*
 			 * This is safe to do even for tables which don't exist or have
 			 * already been invalidated because this is just a deletion/marking