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

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https://hg.mozilla.org/integration/gaia-2_1/rev/2bf7dbff03e6
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #24217 from julienw/1038548-fake-timers a=tests

Bug 1038548 - Intermittent statusbar_test.js | system/Statusbar "after e...
(cherry picked from commit 01f39304bd4518400eb82cdbf72c457f047793a5)
Bumping manifests a=b2g-bump