Fixing memory leaks observed in ASan (babelfish-for-postgresql#4690)

This commit fixes memory leaks observed when testing with ASan

1. In the function TdsSendRowDescription() , strdup() allocates memory using the system's malloc(), which is completely outside PostgreSQL's memory management. This means the string stored in relMetaDataInfo->partName[1] lives in malloc-heap, not in any PostgreSQL memory context.
By using pstrdup() , it allocates using palloc() inside the current memory context (MessageContext), so it's properly tracked and will be freed when that context is destroyed.

2. Similarly in the function rewrite_if_condition(), strdup uses malloc which is invisible to PostgreSQL's memory management while pstrdup allocates in the current memory context, which gets cleaned up automatically.

Task: BABEL-6422

Authored by : harshdu@amazon.com

Author: harshdubey166

contrib/babelfishpg_tds/src/backend/tds/tdsresponse.c

@@ -1636,8 +1636,13 @@ PrepareRowDescription(TupleDesc typeinfo, PlannedStmt *plannedstmt, List *target
 				 * schema name only assuming its shared schema.
 				 */
 				if (relMetaDataInfo->partName[1] == NULL)
-					relMetaDataInfo->partName[1] = strdup(physical_schema_name);
-
+				{
+					if (physical_schema_name != NULL)
+						relMetaDataInfo->partName[1] = pstrdup(physical_schema_name);
+					else
+						relMetaDataInfo->partName[1] = NULL;
+				}
+				
 				if (physical_schema_name)
 					pfree(physical_schema_name);
 

contrib/babelfishpg_tsql/src/tsqlIface.cpp

@@ -2999,7 +2999,7 @@ class tsqlBuilder : public tsqlCommonMutator
 		clear_rewritten_query_fragment();
 
 		/* Now we can prepend SELECT to rewritten search_condition */
-		expr->query = strdup((std::string("SELECT ") + std::string(expr->query)).c_str());
+		expr->query = pstrdup((std::string("SELECT ") + std::string(expr->query)).c_str());
 		return expr;
 	}