Remove initialization of MyClientConnectionInfo at backend startup

This stuff should be already initialized at process startup, so adding
this extra step is confusing for no gain.

Per gripe from Tom Lane and Jacob Champion.

Discussion: https://postgr.es/m/bbf2b922-4ff7-5c30-e3ef-2a8bdcdd1116@timescale.com

src/backend/postmaster/postmaster.c

@@ -4305,7 +4305,6 @@ BackendInitialize(Port *port)
 
 	/* Save port etc. for ps status */
 	MyProcPort = port;
-	memset(&MyClientConnectionInfo, 0, sizeof(MyClientConnectionInfo));
 
 	/* Tell fd.c about the long-lived FD associated with the port */
 	ReserveExternalFD();