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

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https://hg.mozilla.org/integration/gaia-central/rev/ab8396fcb14d
Author: Jared Hirsch <ohai@6a68.net>
Desc: Merge pull request #21204 from 6a68/bug-1028943-fmd-erase-media

Bug 1028943 - Only factoryReset() after all calls to delete() finish. r=...

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https://hg.mozilla.org/integration/gaia-central/rev/09a66510f69d
Author: Guilherme Goncalves <guilherme.p.gonc@gmail.com>
Desc: Bug 1028943 - Only factoryReset() after all calls to delete() finish. r=dougt a=bailey
Bumping manifests a=b2g-bump