More db.DefaultContext refactor (#27265)

Part of #27065

This PR touches functions used in templates. As templates are not static
typed, errors are harder to find, but I hope I catch it all. I think
some tests from other persons do not hurt.

models/issues/comment_code.go

@@ -99,11 +99,11 @@ func findCodeComments(ctx context.Context, opts FindCommentsOptions, issue *Issu
 		comments[n] = comment
 		n++
 
-		if err := comment.LoadResolveDoer(); err != nil {
+		if err := comment.LoadResolveDoer(ctx); err != nil {
 			return nil, err
 		}
 
-		if err := comment.LoadReactions(issue.Repo); err != nil {
+		if err := comment.LoadReactions(ctx, issue.Repo); err != nil {
 			return nil, err
 		}