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

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https://hg.mozilla.org/integration/gaia-central/rev/15549e4e4816
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 972600 - [B2G][Contacts] After merging duplicate contacts selecting edit contact button brings up 'Add contact' screen"

This reverts commit 8e41704de226a75ce5ce6420b70016f39eb57ea6.

Reverting test due to intermittent test failure.
Bumping manifests a=b2g-bump