!4364 修复gs_ctl query时sync_most_available值不正确的问题

Merge pull request !4364 from Movead/5.0.0

src/gausskernel/process/postmaster/postmaster.cpp

@@ -5583,6 +5583,9 @@ static void SIGHUP_handler(SIGNAL_ARGS)
         LWLockRelease(ConfigFileLock);
         NotifyGscSigHup();
 
+        most_available_sync = (volatile bool) u_sess->attr.attr_storage.guc_most_available_sync;
+        SyncRepUpdateSyncStandbysDefined();
+
         (void)SignalChildren(SIGHUP);
         if (ENABLE_THREAD_POOL) {
             g_threadPoolControler->GetSessionCtrl()->SigHupHandler();