DEV: Remove full group refreshes from tests (#25414)

We have all these calls to Group.refresh_automatic_groups! littered throughout the tests. Including tests that are seemingly unrelated to groups. This is because automatic group memberships aren't fabricated when making a vanilla user. There are two places where you'd want to use this:

You have fabricated a user that needs a certain trust level (which is now based on group membership.)
You need the system user to have a certain trust level.
In the first case, we can pass refresh_auto_groups: true to the fabricator instead. This is a more lightweight operation that only considers a single user, instead of all users in all groups.

The second case is no longer a thing after #25400.

spec/serializers/basic_group_serializer_spec.rb

@@ -42,19 +42,16 @@ RSpec.describe BasicGroupSerializer do
   describe "#has_messages" do
     fab!(:group) { Fabricate(:group, has_messages: true) }
 
-    before { Group.refresh_automatic_groups! }
-
     describe "for a staff user" do
-      let(:guardian) { Guardian.new(Fabricate(:moderator)) }
+      let!(:guardian) { Guardian.new(Fabricate(:moderator)) }
 
       it "should be present" do
-        Group.refresh_automatic_groups!
         expect(serializer.as_json[:has_messages]).to eq(true)
       end
     end
 
     describe "for a group user" do
-      fab!(:user)
+      fab!(:user) { Fabricate(:user, refresh_auto_groups: true) }
       let(:guardian) { Guardian.new(user) }
 
       before { group.add(user) }