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

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https://hg.mozilla.org/integration/gaia-central/rev/b9f7d6b832ff
Author: Martijn <martijn.martijn@gmail.com>
Desc: Merge pull request #26803 from mwargers/cost_control_ftu

Bug 1097605 - Update method for getting mobile data state in Usage app

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https://hg.mozilla.org/integration/gaia-central/rev/a4f0400b58c5
Author: Martijn Wargers <mwargers@mozilla.com>
Desc: Bug 1097605 - Update method for getting mobile data state in Usage app
Bumping manifests a=b2g-bump