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

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https://hg.mozilla.org/integration/gaia-central/rev/68ab6aee86cf
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Merge pull request #23517 from mikehenrty/bug-1042713-reland-ambient

[Bug-1042713] Remove notification icons r=mhenretty

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https://hg.mozilla.org/integration/gaia-central/rev/e51c82b235bf
Author: albertopq <albert.pastor@gmail.com>
Desc: [Bug-1042713] Remove notification icons r=mhenretty
Bumping manifests a=b2g-bump