Extending Century switch.

The owner of the switch is on holiday.
Remove unreliable test for CDN
Tidy up some tests
Approve new style R2 ad units

R2 ad units will now have the same format as NextGen. However, the new
units must now be approved manually too.
Tighten ad unit filter to 4 segments

Domain/section/contenttype/platform
Add test data
Fix padding issues on multimedia banding
Stop putting the old metrics
Remove the old latency metrics
Stray letter
limit width of l-side-margins
Pass through the inline video player end slate path on fronts
Add playable videos to multimedia container
Merge pull request #5453 from guardian/century-switch

Extending Century switch.
Pass in layoutType to multimedia container via controller.
Merge pull request #5465 from guardian/video-tweaks

Fix padding issues on multimedia banding
Fix margin issue
Move video container margin rules to appropriate container css files
Merge remote-tracking branch 'origin/master' into supportR2InAdUnitApprovalApp
correct targeting