Bumping gaia.json for 1 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/6127157a7933
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #11564 from lightsofapollo/travis-mc

Bug 905875 - Switch unit tests to mozilla-central