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

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https://hg.mozilla.org/integration/gaia-central/rev/2cb912d4cd59
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Merge pull request #22376 from mikehenrty/bug-1044984-disabled

Bug 1044984 - disabled intermittent worker_test.js, a=test-only

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https://hg.mozilla.org/integration/gaia-central/rev/df0b200f0233
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 1044984 - disabled intermittent worker_test.js, a=test-only
Bumping manifests a=b2g-bump