MDB-40410: Allow to kill backends which have application_name starting with "MDB" instead of exactly matching

Author: vicpopov

src/backend/storage/ipc/signalfuncs.c

@@ -97,7 +97,7 @@ pg_signal_backend(int pid, int sig)
 
 		if (local_beentry->backendStatus.st_backendType == B_AUTOVAC_WORKER) {
 			// ok
-		} else if (appname != NULL && strcmp(appname, "MDB") == 0) {
+		} else if (appname != NULL && strncmp(appname, "MDB", 3) == 0) {
 			// ok
 		} else {
 			return SIGNAL_BACKEND_NOSUPERUSER;