DEV: Reset OmniAuth test mode between tests (#15278)

OmniAuth test mode is disabled by default, so that we can integration-test the omniauth strategies. Sometimes, we manually enable test mode for specific specs. This commit ensures that test_mode is always disabled again after each spec.

spec/rails_helper.rb

@@ -154,6 +154,8 @@ module TestSetup
 
     # Don't queue badge grant in test mode
     BadgeGranter.disable_queue
+
+    OmniAuth.config.test_mode = false
   end
 end