Some fixes of the prompt of new branches (#26257)

Related to #26239

This PR makes some fixes:
- do not show the prompt for mirror repos and repos with pull request
units disabled
- use `commit_time` instead of `updated_unix`, as `commit_time` is the
real time when the branch was pushed

models/git/branch.go

@@ -395,9 +395,9 @@ func FindRecentlyPushedNewBranches(ctx context.Context, repoID, userID int64, ex
 		Where("pusher_id=? AND is_deleted=?", userID, false).
 		And("name <> ?", excludeBranchName).
 		And("repo_id = ?", repoID).
-		And("updated_unix >= ?", time.Now().Add(-time.Hour*6).Unix()).
+		And("commit_time >= ?", time.Now().Add(-time.Hour*6).Unix()).
 		NotIn("name", subQuery).
-		OrderBy("branch.updated_unix DESC").
+		OrderBy("branch.commit_time DESC").
 		Limit(2).
 		Find(&branches)
 	return branches, err

routers/web/repo/view.go

@@ -999,12 +999,20 @@ func renderCode(ctx *context.Context) {
 			ctx.ServerError("GetBaseRepo", err)
 			return
 		}
+
+		showRecentlyPushedNewBranches := true
+		if ctx.Repo.Repository.IsMirror ||
+			!ctx.Repo.Repository.UnitEnabled(ctx, unit_model.TypePullRequests) {
+			showRecentlyPushedNewBranches = false
+		}
+		if showRecentlyPushedNewBranches {
 			ctx.Data["RecentlyPushedNewBranches"], err = git_model.FindRecentlyPushedNewBranches(ctx, ctx.Repo.Repository.ID, ctx.Doer.ID, ctx.Repo.Repository.DefaultBranch)
 			if err != nil {
 				ctx.ServerError("GetRecentlyPushedBranches", err)
 				return
 			}
 		}
+	}
 
 	var treeNames []string
 	paths := make([]string, 0, 5)

templates/repo/code/recently_pushed_new_branches.tmpl

@@ -1,7 +1,7 @@
 {{range .RecentlyPushedNewBranches}}
 	<div class="ui positive message gt-df gt-ac">
 		<div class="gt-f1">
-			{{$timeSince := TimeSince .UpdatedUnix.AsTime $.locale}}
+			{{$timeSince := TimeSince .CommitTime.AsTime $.locale}}
 			{{$.locale.Tr "repo.pulls.recently_pushed_new_branches" (PathEscapeSegments .Name) $timeSince | Safe}}
 		</div>
 		<a aria-role="button" class="ui compact positive button gt-m-0" href="{{$.Repository.ComposeBranchCompareURL $.Repository.BaseRepo (PathEscapeSegments .Name)}}">