forbid use gsc in fenced udf mode

src/common/backend/utils/cache/knl_localsysdbcache.cpp

@@ -147,6 +147,10 @@ void ResetDeepthInAcceptInvalidationMessage(int value)
 
 static bool SwitchToSessionSysCache()
 {
+    /* fenced mode not use gsc */
+    if (FencedUDFMasterMode) {
+        return true;
+    }
     if (
 #ifdef ENABLE_MULTIPLE_NODES
         /* ts code dont use gsc */
@@ -1214,4 +1218,4 @@ void TryFreshSmgrCache(struct SMgrRelationData *smgr)
     smgr->xact_seqno = t_thrd.lsc_cxt.xact_seqno;
     /* reset it and so caller will reload smgr_targblock */
     smgr->smgr_targblock = InvalidBlockNumber;
-}
+}