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

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https://hg.mozilla.org/integration/gaia-central/rev/a4cf86366073
Author: russnicoletti <rnicoletti@mozilla.com>
Desc: Merge pull request #25627 from russnicoletti/bug-1079519

Bug 1079519 - Unable to play video clips during WEBRTC video call r=djf

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https://hg.mozilla.org/integration/gaia-central/rev/faae09ba9e80
Author: Russ Nicoletti <rnicoletti@mozilla.com>
Desc: Bug 1079519 - Unable to play video clips during WEBRTC video call
Bumping manifests a=b2g-bump