Fix listPathRaw/WalkDir cancelation (#11905)

In #11888 we observe a lot of running, WalkDir calls.

There doesn't appear to be any listerners for these calls, so they should be aborted.

Ensure that WalkDir aborts when upstream cancels the request.

Fixes #11888

cmd/common-main.go

@@ -428,3 +428,13 @@ func getTLSConfig() (x509Certs []*x509.Certificate, manager *certs.Manager, secu
 	secureConn = true
 	return x509Certs, manager, secureConn, nil
 }
+
+// contextCanceled returns whether a context is canceled.
+func contextCanceled(ctx context.Context) bool {
+	select {
+	case <-ctx.Done():
+		return true
+	default:
+		return false
+	}
+}