fix: code search title translation (#22285)

`code.title` isn't an existing translation.

`explore.code` is the translation used for the tab, which I think
matches closely enough for this instead of a brand new translation.

Open to feedback on whether a new translation would be preferred
instead.

Signed-off-by: jolheiser <john.olheiser@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

routers/web/user/code.go

@@ -26,7 +26,7 @@ func CodeSearch(ctx *context.Context) {
 
 	ctx.Data["IsPackageEnabled"] = setting.Packages.Enabled
 	ctx.Data["IsRepoIndexerEnabled"] = setting.Indexer.RepoIndexerEnabled
-	ctx.Data["Title"] = ctx.Tr("code.title")
+	ctx.Data["Title"] = ctx.Tr("explore.code")
 	ctx.Data["ContextUser"] = ctx.ContextUser
 
 	language := ctx.FormTrim("l")