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

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https://hg.mozilla.org/integration/gaia-central/rev/84ef8bdba0d8
Author: Zac <zcampbell@mozilla.com>
Desc: Revert "Bug 1021732 - [Flame] Re-enable test_privileged_app_contacts_prompt"

This reverts commit ea11b14e0639ea03a1e430e1102a554c92330262.
Bumping manifests a=b2g-bump