Fix improper HTMLURL usages in Go code (#22839)

In Go code, HTMLURL should be only used for external systems, like
API/webhook/mail/notification, etc.

If a URL is used by `Redirect` or rendered in a template, it should be a
relative URL (aka `Link()` in Gitea)

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

services/actions/commit_status.go

@@ -59,7 +59,7 @@ func CreateCommitStatus(ctx context.Context, job *actions_model.ActionRunJob) er
 		Creator: creator,
 		CommitStatus: &git_model.CommitStatus{
 			SHA:         sha,
-			TargetURL:   run.HTMLURL(),
+			TargetURL:   run.Link(),
 			Description: "",
 			Context:     ctxname,
 			CreatorID:   payload.Pusher.ID,