More Logging of Leak Plug

It behaves differently in prod would you believe.
Effect should be that there is no longer a thread local
in the finalizer thread.
dont' convert images to bufferedimages when we don't need to, and don't write to a disk before imagemagic as it's slow
minor template fixes
use js- for dfp hook
fix test
Merge pull request #7482 from guardian/correct-dfp-js-hook

Use js- class hook for DFP ad slots
cr fix
Merge pull request #7477 from guardian/manual-multi-fixes

Minor manual multiple template fixes
Merge pull request #7463 from guardian/kc-plumbing-log

Add Logging to Memory Leak Plug
Merge pull request #7464 from guardian/quicker-png-resizer

speed up png resizer
Merge branch 'master' of github.com:guardian/frontend into mobile-flyers

* 'master' of github.com:guardian/frontend:
  cr fix
  fix test
  use js- for dfp hook
  minor template fixes
  dont' convert images to bufferedimages when we don't need to, and don't write to a disk before imagemagic as it's slow
  More Logging of Leak Plug