Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/4a6709281ab8
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 909689 - Set data connection text based on the network mode and the existence of calls r=alive