!1110 修复startup线程没有上报信息给pgstat，导致pg_os_threads查看不到线程信息的问题

Merge pull request !1110 from TotaJ/backend

src/gausskernel/process/postmaster/startup.cpp

@@ -241,6 +241,8 @@ void StartupProcessMain(void)
     (void)gs_signal_unblock_sigusr2();
 
     SetStaticConnNum();
+    pgstat_report_appname("Startup");
+    pgstat_report_activity(STATE_IDLE, NULL);
 
     if (dummyStandbyMode) {
         StartupDummyStandby();