Refactor user & avatar (#33433)

1. better GetPossibleUserByID logic
2. fix some function name & comment typos
3. do not re-generate avatar if one exists

services/actions/notifier_helper.go

@@ -117,7 +117,7 @@ func (input *notifyInput) Notify(ctx context.Context) {
 
 func notify(ctx context.Context, input *notifyInput) error {
 	shouldDetectSchedules := input.Event == webhook_module.HookEventPush && input.Ref.BranchName() == input.Repo.DefaultBranch
-	if input.Doer.IsActions() {
+	if input.Doer.IsGiteaActions() {
 		// avoiding triggering cyclically, for example:
 		// a comment of an issue will trigger the runner to add a new comment as reply,
 		// and the new comment will trigger the runner again.