DEV: Automatically update groups for test users with explicit TL (#25415)

For performance reasons we don't automatically add fabricated users to trust level auto-groups. However, when explicitly passing a trust level to the fabricator, in 99% of cases it means that trust level is relevant for the test, and we need the groups.

This change makes it so that when a trust level is explicitly passed to the fabricator, the auto-groups are refreshed. There's no longer a need to also pass refresh_auto_groups: true, which means clearer tests, fewer mistakes, and less confusion.

spec/lib/new_post_manager_spec.rb

@@ -467,7 +467,7 @@ RSpec.describe NewPostManager do
   end
 
   describe "user needs approval?" do
-    fab!(:user) { Fabricate(:user, trust_level: TrustLevel[0], refresh_auto_groups: true) }
+    fab!(:user) { Fabricate(:user, trust_level: TrustLevel[0]) }
 
     it "handles post_needs_approval? correctly" do
       user.user_stat = UserStat.new(post_count: 0, new_since: DateTime.now)