REFACTOR: Move queue_jobs out of SiteSetting

It is not a setting, and only relevant in specs. The new API is:

```
Jobs.run_later!        # jobs will be thrown on the queue
Jobs.run_immediately!  # jobs will run right away, avoid the queue
```

plugins/discourse-narrative-bot/spec/discourse_narrative_bot/advanced_user_narrative_spec.rb

@@ -22,7 +22,7 @@ RSpec.describe DiscourseNarrativeBot::AdvancedUserNarrative do
   let(:reset_trigger) { DiscourseNarrativeBot::TrackSelector.reset_trigger }
 
   before do
-    run_jobs_synchronously!
+    Jobs.run_immediately!
     SiteSetting.discourse_narrative_bot_enabled = true
   end
 

plugins/discourse-narrative-bot/spec/discourse_narrative_bot/new_user_narrative_spec.rb

@@ -25,7 +25,7 @@ describe DiscourseNarrativeBot::NewUserNarrative do
   let(:reset_trigger) { DiscourseNarrativeBot::TrackSelector.reset_trigger }
 
   before do
-    run_jobs_synchronously!
+    Jobs.run_immediately!
     SiteSetting.discourse_narrative_bot_enabled = true
   end
 

plugins/discourse-narrative-bot/spec/discourse_narrative_bot/track_selector_spec.rb

@@ -37,7 +37,7 @@ describe DiscourseNarrativeBot::TrackSelector do
   end
 
   before do
-    run_jobs_synchronously!
+    Jobs.run_immediately!
   end
 
   describe '#select' do

plugins/discourse-narrative-bot/spec/user_spec.rb

@@ -13,7 +13,7 @@ describe User do
   end
 
   before do
-    run_jobs_synchronously!
+    Jobs.run_immediately!
     SiteSetting.discourse_narrative_bot_enabled = true
   end