Remove unused debugging timeout in relcache

Debug_gp_relation_node_fetch_wait_for_debugging was added to assist
debugging an issue in the RelationFetchGpRelationNodeForXLog recursion
guard. The bug was not reproduced but the GUC was left in when the
ticket was closed so remove. If we need to debug this in the future
we should add something back then.

src/backend/utils/cache/relcache.c

@@ -744,36 +744,12 @@ RelationFetchGpRelationNodeForXLog_Index(
 
 	if (deep >= 2)
 	{
-		int saveDeep;
-
-		if (Debug_gp_relation_node_fetch_wait_for_debugging)
-		{
-			/* Code for investigating MPP-16395, will be removed as part of the fix */
-			elog(WARNING, "RelationFetchGpRelationNodeForXLog_Index [%d] for non-heap %u/%u/%u (deep %d) -- waiting for debug attach...",
-				 countInThisBackend,
-				 relation->rd_node.spcNode,
-				 relation->rd_node.dbNode,
-				 relation->rd_node.relNode,
-				 deep);
-
-			for (int i=0; i < 24 * 60; i++)
-			{
-				pg_usleep(60000000L); /* 60 sec */
-			}
-		}
-
-		/*
-		 * Reset counter in case the user continues to use the session.
-		 */
-		saveDeep = deep;
-		deep = 0;
-
 		elog(ERROR, "RelationFetchGpRelationNodeForXLog_Index [%d] for non-heap %u/%u/%u (deep %d)",
 			 countInThisBackend,
 			 relation->rd_node.spcNode,
 			 relation->rd_node.dbNode,
 			 relation->rd_node.relNode,
-			 saveDeep);
+			 deep);
 	}
 
 	RelationFetchSegFile0GpRelationNode(relation);

src/backend/utils/misc/guc_gp.c

@@ -168,7 +168,6 @@ int			Debug_appendonly_bad_header_print_level = ERROR;
 bool		Debug_appendonly_print_datumstream = false;
 bool		Debug_appendonly_print_visimap = false;
 bool		Debug_appendonly_print_compaction = false;
-bool		Debug_gp_relation_node_fetch_wait_for_debugging = false;
 bool		gp_crash_recovery_abort_suppress_fatal = false;
 bool		gp_persistent_statechange_suppress_error = false;
 bool		Debug_bitmap_print_insert = false;
@@ -1624,16 +1623,6 @@ struct config_bool ConfigureNamesBool_gp[] =
 		false, NULL, NULL
 	},
 
-	{
-		{"debug_gp_relation_node_fetch_wait_for_debugging", PGC_SUSET, DEVELOPER_OPTIONS,
-			gettext_noop("Wait for debugger attach for MPP-16395 RelationFetchGpRelationNodeForXLog issue."),
-			NULL,
-			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
-		},
-		&Debug_gp_relation_node_fetch_wait_for_debugging,
-		false, NULL, NULL
-	},
-
 	{
 		{"debug_xlog_insert_print", PGC_SUSET, DEVELOPER_OPTIONS,
 			gettext_noop("Print XLOG Insert record debugging information."),