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
Pass through the inline video player end slate path on fronts
Merge remote-tracking branch 'origin/master' into supportR2InAdUnitApprovalApp
Merge branch 'master' into supportR2InAdUnitApprovalApp
extend WorldCupWallchartEmbedSwitch, WorldCupArticleContainerSwitch
Merge pull request #5472 from guardian/extend-switches

Extend WorldCupWallchartEmbedSwitch, WorldCupArticleContainerSwitch
Merge pull request #5461 from guardian/supportR2InAdUnitApprovalApp

Support r2 in ad unit approval app
Merge pull request #5469 from guardian/use-correct-endslate-url

Pass through the inline video player end slate path on fronts
Do not show related component for children's book sites
Merge pull request #5474 from guardian/childrens-site-related

Do not show related component for children's book sites
run ab tests once
ab test