Show empty repos in Admin Repository Management page (#23114)

The **Admin Repository Management** page and the **Explore Repository**
page both use the `RenderRepoSearch` function. In this function, the
`OnlyShowRelevant` search option is `true` when querying repositories
for admin page.


https://github.com/go-gitea/gitea/blob/edf98a2dc30956c8e04b778bb7f1ce55c14ba963/routers/web/explore/repo.go#L99-L115

Refer to
[#19361](https://github.com/go-gitea/gitea/pull/19361/files#diff-8058dfb85557010e0592d586675ec62ce406af7068e6311f39c160deac37f149R497),
the repositories with `is_empty=true` will be hidden if
`OnlyShowRelevant` is `true`.

Administrators should be able to see all repositories. So
`OnlyShowRelevant` shouldn't be set to `true` .

---------

Co-authored-by: Andrew Thornton <art27@cantab.net>

routers/web/admin/repos.go

@@ -33,9 +33,10 @@ func Repos(ctx *context.Context) {
 	ctx.Data["PageIsAdminRepositories"] = true
 
 	explore.RenderRepoSearch(ctx, &explore.RepoSearchOptions{
-		Private:  true,
-		PageSize: setting.UI.Admin.RepoPagingNum,
-		TplName:  tplRepos,
+		Private:          true,
+		PageSize:         setting.UI.Admin.RepoPagingNum,
+		TplName:          tplRepos,
+		OnlyShowRelevant: false,
 	})
 }