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

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https://hg.mozilla.org/integration/gaia-central/rev/2cbef3a6df79
Author: Zac <zcampbell@mozilla.com>
Desc: Revert "Bug 943897 - Code timeout into contacts_settings.tap_import_from_sim()"

This reverts commit d17ff0ce155fabec56117be7f0f865feea929703.
Bumping manifests a=b2g-bump