Code Formats, Nits & Unused Func/Var deletions (#15286)

* _ to unused func options

* rm useless brakets

* rm trifial non used models functions

* rm dead code

* rm dead global vars

* fix routers/api/v1/repo/issue.go

* dont overload import module

services/pull/merge.go

@@ -98,7 +98,7 @@ func Merge(pr *models.PullRequest, doer *models.User, baseGitRepo *git.Repositor
 		if err = ref.Issue.LoadRepo(); err != nil {
 			return err
 		}
-		close := (ref.RefAction == references.XRefActionCloses)
+		close := ref.RefAction == references.XRefActionCloses
 		if close != ref.Issue.IsClosed {
 			if err = issue_service.ChangeStatus(ref.Issue, doer, close); err != nil {
 				return err