Fix profile list when profiles directory is missing

This was reported in [1] and fixed in [2] in 2019, but later it was
broken by [3] in commit c3aafae.

`listProfiles()` can return `os.ErrNotExist` from `os.ReadDir()` so it
must be tested with `os.IsNotExist()`.

[1] kubernetes#5898
[2] kubernetes#5955
[3] kubernetes#6440

cmd/minikube/cmd/config/profile_list.go

@@ -205,7 +205,7 @@ func printProfilesJSON() {
 	updateProfilesStatus(validProfiles)
 
 	var body = map[string]interface{}{}
-	if err == nil || config.IsNotExist(err) {
+	if err == nil || os.IsNotExist(err) {
 		body["valid"] = profilesOrDefault(validProfiles)
 		body["invalid"] = profilesOrDefault(invalidProfiles)
 		jsonString, _ := json.Marshal(body)