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

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https://hg.mozilla.org/integration/gaia-central/rev/935003c5812f
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #13800 from bebef1987/xfail_cost

Bug 939722 - Xfail test_cost_control_data_alert_mobile

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https://hg.mozilla.org/integration/gaia-central/rev/712645e10b5c
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 939722 - Xfail test_cost_control_data_alert_mobile