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

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https://hg.mozilla.org/integration/gaia-central/rev/ffbb39b4a204
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #22685 from gregarndt/bug_1049477

Bug 1049477 - Remove logic from test_lockscreen_unlock_to_emergency_call...

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https://hg.mozilla.org/integration/gaia-central/rev/8ed3688a930a
Author: Greg Arndt <garndt@mozilla.com>
Desc: Bug 1049477 - Remove logic from test_lockscreen_unlock_to_emergency_call_screen.py
Bumping manifests a=b2g-bump