DEV: Disable SearchIndexer after fabrication (#21378)

SearchIndexer is only automatically disabled in `before_all` and `before` blocks which means at the start
of test runs. Enabling the SearchIndexer in one `fab!` block will affect
all other `fab!` blocks which is not ideal as we may be indexing stuff
for search when we don't need to.

spec/models/topic_spec.rb

@@ -653,8 +653,9 @@ RSpec.describe Topic do
 
     context "with a similar topic" do
       fab!(:post) do
-        SearchIndexer.enable
-        create_post(title: "Evil trout is the dude who posted this topic")
+        with_search_indexer_enabled do
+          create_post(title: "Evil trout is the dude who posted this topic")
+        end
       end
 
       let(:topic) { post.topic }