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

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https://hg.mozilla.org/integration/gaia-central/rev/b3f50a607eba
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #16044 from viorelaioia/bug_967410

Bug 967410 - Update all tests in master with moztrap test case IDs in th...

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https://hg.mozilla.org/integration/gaia-central/rev/a42f880847ce
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 967410 - Update all tests in master with moztrap test case IDs in the docstring
Bumping manifests a=b2g-bump