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/3e5a492e286f
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #12264 from crh0716/917238

Bug 917238 - Load network.json for supported network types r=evelyn(cherry picked from commit 4d28cf400b523e26d22b3a5ebe15a75764e48390)