Reduce timeouts on SearchController#count to 5s

The current timeout defaults to 15s. Per
https://gitlab.com/gitlab-org/gitlab/-/issues/327106 this endpoint
consumes a considerable amount of DB time. Since this endpoint is not as
essential as the primary task the user is performing (since it is used
to generate tab counts for other tabs you aren't searching) it makes
sense to reduce the timeout so slower counts don't consume too much
resources.

app/controllers/search_controller.rb

@@ -47,7 +47,11 @@ class SearchController < ApplicationController
     params.require([:search, :scope])
 
     scope = search_service.scope
+
+    count = 0
+    ApplicationRecord.with_fast_read_statement_timeout do
       count = search_service.search_results.formatted_count(scope)
+    end
 
     # Users switching tabs will keep fetching the same tab counts so it's a
     # good idea to cache in their browser just for a short time. They can still

changelogs/unreleased/327106-reduce-timeout-on-search-count.yml

+---
+title: Reduce timeouts on tab counts for searches to 5s
+merge_request: 59435
+author:
+type: performance