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/lib/email/receiver_spec.rb

@@ -1687,8 +1687,6 @@ RSpec.describe Email::Receiver do
       category.set_permissions(Group[:trust_level_4] => :full)
       category.save!
 
-      Group.refresh_automatic_group!(:trust_level_4)
-
       expect { process(:tl3_user) }.to raise_error(Email::Receiver::InvalidPost)
       expect { process(:tl4_user) }.to change(Topic, :count)
     end