cleanup locale function usage (#27227) (#27240)

Backport #27227 by @denyskon

Throughout the Gitea codebase, you can meet some weird constructions to
make `locale.Tr` work in subtemplates.
Since we now have `ctx.Locale.Tr` which solves that problem, clean up
various templates which pass `locale` through `dict` or use some weird
constructions like `$.root.locale`

Going on, it would be great to replace every case of `$.locale.Tr` and
`.locale.Tr` with `ctx.Locale.Tr`, but that needs to be done with
patience.

Co-authored-by: Denys Konovalov <kontakt@denyskon.de>

templates/admin/user/list.tmpl

@@ -54,7 +54,7 @@
 
 				<!-- Search Text -->
 				<div class="ui fluid action input">
-					{{template "shared/searchinput" dict "locale" .locale "Value" .Keyword "AutoFocus" true}}
+					{{template "shared/searchinput" dict "Value" .Keyword "AutoFocus" true}}
 					<button class="ui primary button">{{.locale.Tr "explore.search"}}</button>
 				</div>
 			</form>