Fix sort order for organization home and user profile page (#31921)

Fix sort order for organization home and user profile page (#31921)

Fix #31916

In #30876, `sortOrder` has been changed into a map, but it is only
implemented in explore.
~~But it seems that size sort order has no effect from long long ago,~~
not directly caused by the PR above.

I think it is still caused by #29231.
In #29231, it merged the sort orders from
`templates/explore/repo_search.tmpl` and
`templates/admin/repo/search.tmpl`.
In `templates/admin/repo/search.tmpl`, it contains size sort orders, but
not in `templates/explore/repo_search.tmpl`, which is used in non-admin
pages.
So `order by size` is added from #29231, but the handler was not added.

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Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>