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

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https://hg.mozilla.org/integration/gaia-central/rev/73ffd2cf46aa
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 1109606 - Add a test to check that a miss call notification is cleared even if a voicemail notification is present"

This reverts commit 3ae6af8d7c1ac08abd589316f4a634e0064e86f2.
Bumping manifests a=b2g-bump