core: close stdoutPipe for the discovery daemon

Closing stdoutPipe for the discovery daemon that
could possibly leaks memory due to unclosed resources.

Closes: #8914
Signed-off-by: subhamkrai <srai@redhat.com>

pkg/daemon/discover/discover.go

@@ -158,6 +158,7 @@ func rawUdevBlockMonitor(c chan string, matches, exclusions []string) {
 		logger.Warningf("Cannot open udevadm stdout: %v", err)
 		return
 	}
+	defer stdout.Close()
 
 	err = cmd.Start()
 	if err != nil {