fix(backend): Skip cdb_setup/cdb_cleanup for auxiliary background workers

Fix issue apache#1389: Auxiliary processes (ftsprobe, global deadlock detector,
dtx recovery, sweeper, pg_cron launcher) currently open unnecessary
network sockets for interconnect communication they don't need.

Per review feedback, instead of adding checks inside cdb_setup/cdb_cleanup
functions, skip calling these functions entirely for auxiliary background
workers in InitPostgres().

This resolves the security concern of having unnecessary open network
ports and reduces resource usage.

Author: zhan7236

src/backend/utils/init/postinit.c

@@ -1267,8 +1267,14 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
      * Primary function is to establish connections to the qExecs.
      * This is SKIPPED when the database is in bootstrap mode or 
      * Is not UnderPostmaster.
+     *
+     * Also skip for auxiliary background workers (e.g., ftsprobe, global
+     * deadlock detector, dtx recovery, sweeper, pg_cron launcher). These
+     * processes don't require interconnect for data exchange and opening
+     * unnecessary network sockets may be considered a security issue.
      */
-    if (!bootstrap && IsUnderPostmaster && !IsLoginMonitorWorkerProcess())
+    if (!bootstrap && IsUnderPostmaster && !IsLoginMonitorWorkerProcess() &&
+        !amAuxiliaryBgWorker())
     {
 		cdb_setup();
 		on_proc_exit( cdb_cleanup, 0 );