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/models/post_spec.rb

@@ -359,8 +359,6 @@ RSpec.describe Post do
     end
 
     describe "embedded_media_allowed_groups" do
-      before { Group.refresh_automatic_groups! }
-
       it "doesn't allow users outside of `embedded_media_post_allowed_groups`" do
         SiteSetting.embedded_media_post_allowed_groups = Group::AUTO_GROUPS[:trust_level_4]
         post_one_image.user.change_trust_level!(3)