Fix issue label deletion with Actions tokens (#37013)

Use shared repo permission resolution for Actions task users in issue
label remove and clear paths, and add a regression test for deleting
issue labels with a Gitea Actions token.

This fixes issue label deletion when the request is authenticated with a
Gitea Actions token.
Fixes #37011 

The bug was that the delete path re-resolved repository permissions
using the normal user permission helper, which does not handle Actions
task users. As a result, `DELETE
/api/v1/repos/{owner}/{repo}/issues/{index}/labels/{id}` could return
`500` for Actions tokens even though label listing and label addition
worked.

---------

Co-authored-by: Codex <codex@openai.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>

services/markup/renderhelper_issueicontitle.go

@@ -43,7 +43,7 @@ func renderRepoIssueIconTitle(ctx context.Context, opts markup.RenderIssueIconTi
 	}
 
 	if webCtx.Repo.Repository == nil || dbRepo.ID != webCtx.Repo.Repository.ID {
-		perms, err := access.GetUserRepoPermission(ctx, dbRepo, webCtx.Doer)
+		perms, err := access.GetDoerRepoPermission(ctx, dbRepo, webCtx.Doer)
 		if err != nil {
 			return "", err
 		}