Don't require a DB connection, but release one if it is acquired (#1812)

sentry-rails/lib/sentry/rails/background_worker.rb

@@ -1,15 +1,10 @@
 module Sentry
   class BackgroundWorker
     def _perform(&block)
-      # some applications have partial or even no AR connection
-      if ActiveRecord::Base.connected?
-        # make sure the background worker returns AR connection if it accidentally acquire one during serialization
-        ActiveRecord::Base.connection_pool.with_connection do
-          block.call
-        end
-      else
-        block.call
-      end
+      block.call
+    ensure
+      # make sure the background worker returns AR connection if it accidentally acquire one during serialization
+      ActiveRecord::Base.connection_pool.release_connection
     end
   end
 end