Bumping gaia.json for 2 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/a2558b6beaa8
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #13747 from bobsilverberg/bug939062-v1.2

Bug 939062 - Improve wait in test_add_contact_to_favorites.py

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https://hg.mozilla.org/integration/gaia-1_2/rev/442e20abd107
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Bug 939062 - Improve wait in test_add_contact_to_favorites.py