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/dfcd6be35884
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #13969 from bobsilverberg/eme_prob

Bug 939780 - [1.2] Investigate intermittent e.me tests failures on v1.2

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https://hg.mozilla.org/integration/gaia-1_2/rev/7c32715a95f6
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Bug 939780 - [1.2] Investigate intermittent e.me tests failures on aurora