UserDisplay: Handle both service accounts and user names when resolving "createdBy" (#98719)

* Handle both user and service accounts when resolving identity name for dashboards and folders

Co-authored-by: Misi <mgyongyosi@users.noreply.github.com>

pkg/api/folder_test.go

@@ -534,6 +534,7 @@ func (m mockClientConfigProvider) DirectlyServeHTTP(w http.ResponseWriter, r *ht
 
 func TestUpdateFolderLegacyAndUnifiedStorage(t *testing.T) {
 	testuser := &user.User{ID: 99, UID: "fdxsqt7t5ryf4a", Login: "testuser"}
+	testSignedInUser := &user.SignedInUser{UserID: 99, UserUID: "fdxsqt7t5ryf4a", Login: "testuser"}
 
 	legacyFolder := folder.Folder{
 		UID:          "ady4yobv315a8e",
@@ -718,7 +719,8 @@ func TestUpdateFolderLegacyAndUnifiedStorage(t *testing.T) {
 						ExpectedResult: model.HitList{},
 					}
 					hs.userService = &usertest.FakeUserService{
-						ExpectedUser: testuser,
+						ExpectedUser:         testuser,
+						ExpectedSignedInUser: testSignedInUser,
 					}
 					hs.Features = featuremgmt.WithFeatures(
 						featuresArr...,