Remove unused `user` paramater (#17723)

As title

routers/web/repo/compare.go

@@ -433,7 +433,7 @@ func ParseCompareInfo(ctx *context.Context) *CompareInfo {
 		if canRead {
 			ctx.Data["RootRepo"] = rootRepo
 			if !fileOnly {
-				branches, tags, err := getBranchesAndTagsForRepo(ctx.User, rootRepo)
+				branches, tags, err := getBranchesAndTagsForRepo(rootRepo)
 				if err != nil {
 					ctx.ServerError("GetBranchesForRepo", err)
 					return nil
@@ -458,7 +458,7 @@ func ParseCompareInfo(ctx *context.Context) *CompareInfo {
 		if canRead {
 			ctx.Data["OwnForkRepo"] = ownForkRepo
 			if !fileOnly {
-				branches, tags, err := getBranchesAndTagsForRepo(ctx.User, ownForkRepo)
+				branches, tags, err := getBranchesAndTagsForRepo(ownForkRepo)
 				if err != nil {
 					ctx.ServerError("GetBranchesForRepo", err)
 					return nil
@@ -630,7 +630,7 @@ func PrepareCompareDiff(
 	return false
 }
 
-func getBranchesAndTagsForRepo(user *models.User, repo *models.Repository) (branches, tags []string, err error) {
+func getBranchesAndTagsForRepo(repo *models.Repository) (branches, tags []string, err error) {
 	gitRepo, err := git.OpenRepository(repo.RepoPath())
 	if err != nil {
 		return nil, nil, err