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

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https://hg.mozilla.org/integration/gaia-1_4/rev/52f8e018419d
Author: Bebe <bebe@mozilla.ro>
Desc: Disable Bug 999447 - Active sync Inbox seems empty in the tests on Jenkins
Bumping manifests a=b2g-bump