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

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https://hg.mozilla.org/integration/gaia-central/rev/168c5ba3a072
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #21655 from pivanov/bug-1035708

Bug 1035708 - [Bluetooth] - remove unused images

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https://hg.mozilla.org/integration/gaia-central/rev/6835a0ba204a
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 1035708 - [Bluetooth] - remove unused images
Bumping manifests a=b2g-bump