util, GetRuntimeDir: don't error out early if XDG_RUNTIME_DIR is not found

We must try out all possible alternatives for rootless users instead of
failing eary if XDG_RUNTIME_DIR is not set.

Following regression was part of: 5948e6b369

[NO NEW TESTS NEEDED]
[NO TESTS NEEDED]

Signed-off-by: Aditya R <arajan@redhat.com>

common/pkg/util/util_supported.go

@@ -34,8 +34,7 @@ func GetRuntimeDir() (string, error) {
 	rootlessRuntimeDirOnce.Do(func() {
 		runtimeDir, err := homedir.GetRuntimeDir()
 		if err != nil {
-			rootlessRuntimeDirError = err
-			return
+			logrus.Debug(err)
 		}
 		if runtimeDir != "" {
 			st, err := os.Stat(runtimeDir)