Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/d509e1202473
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Merge pull request #21542 from EverythingMe/1016221-cdn-bgs

Bug 1016221 - [Collection App] Mozilla CDN Backgrounds for Collection ic...

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https://hg.mozilla.org/integration/gaia-central/rev/85376c050fbb
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Bug 1016221 - [Collection App] Mozilla CDN Backgrounds for Collection icons
Bumping manifests a=b2g-bump