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

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https://hg.mozilla.org/integration/gaia-central/rev/66fd1b8dceae
Author: Mike Pennisi <mike@mikepennisi.com>
Desc: Revert "Bug 898354 - [User Story] Timer Notification"

This reverts commit 8862901daa7b9befce33d1d679091f26437386d1 due to an
inefficient draw cycle.

Signed-off-by: Mike Pennisi <mike@mikepennisi.com>