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

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https://hg.mozilla.org/integration/gaia-central/rev/3221e2a05eb5
Author: Carsten Book -Tomcat- <cbook@mozilla.com>
Desc: Revert "Bug 938896 - Find My Device client." for breaking tests

This reverts commit 751d4a616f5c8742bc852243b6ed071c20c5a163.
Bumping manifests a=b2g-bump