[cr146] GetDestinationUrlForStarterPackId with StarterPackId

This function's signature has been updated in upstream, and this has to
reflect on the override we have as well.

Chromium changes:
https://chromium.googlesource.com/chromium/src/+/2da6a2e1fcb570ba10d9c1b65bbd742ae9dfbf8d

commit 2da6a2e1fcb570ba10d9c1b65bbd742ae9dfbf8d
Author: Keigo Oka <oka@google.com>
Date:   Tue Jan 27 21:30:24 2026 -0800

    site search: Use enum for StarterPackId

    This allows us to export them to Java later.

    Bug: 399443172
    Change-Id: If3d7fbbc5be844f5f3bf1fdb876a24ea183a2c1c
    Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7512676
    Reviewed-by: Tomasz Wiszkowski <ender@google.com>
    Commit-Queue: Keigo Oka <oka@chromium.org>
    Auto-Submit: Keigo Oka <oka@chromium.org>
    Cr-Commit-Position: refs/heads/main@{#1575696}

chromium_src/components/search_engines/template_url_starter_pack_data.cc

@@ -70,7 +70,7 @@ std::vector<std::unique_ptr<TemplateURLData>> GetStarterPackEngines() {
   return t_urls;
 }
 
-std::u16string GetDestinationUrlForStarterPackId(int id) {
+std::u16string GetDestinationUrlForStarterPackId(StarterPackId id) {
   if (id == StarterPackId::kAskBraveSearch) {
     return base::UTF8ToUTF16(ask_brave_search.destination_url);
   }