Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/6fd6e4be4fa1
Author: Yuren Ju <yurenju@gmail.com>
Desc: Merge pull request #20128 from yurenju/clean-stage-app

Bug 1021569 - rewrite clear-stage-app in javascript r=@cctuan

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https://hg.mozilla.org/integration/gaia-central/rev/ce927b656c1c
Author: Yuren Ju <yurenju@gmail.com>
Desc: Bug 1021569 - rewrite clear-stage-app in javascript

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https://hg.mozilla.org/integration/gaia-central/rev/394e13110d3b
Author: Jared Hirsch <ohai@6a68.net>
Desc: Merge pull request #20710 from 6a68/bug-1027325-fmd-check-passcode-state

Bug 1027325 - Correctly check passcode state from find my device

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https://hg.mozilla.org/integration/gaia-central/rev/b519ba376fc8
Author: Jared Hirsch <ohai@6a68.net>
Desc: Bug 1027325 - Correctly check passcode state from find my device
Bumping manifests a=b2g-bump