chore: Load only required APMs (#6497)

- Disable requiring the gems for all the APMs 
- Switch to selectively requiring them.

spec/lib/chatwoot_exception_tracker_spec.rb

@@ -1,4 +1,6 @@
 require 'rails_helper'
+# explicitly requiring since we are loading apms conditionally in application.rb
+require 'sentry-ruby'
 
 describe ChatwootExceptionTracker do
   it 'use rails logger if no tracker is configured' do