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

========

https://hg.mozilla.org/integration/gaia-central/rev/346855a97344
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Revert "Merge pull request #18680 from stasm/1000895-system-once-ready"

This reverts commit ec49d12262cad25cc0c0bda80dcfeaa619f4d3ce, reversing
changes made to e7debccabc206f6fcc182bd66cfea50f849339a7.
Bumping manifests a=b2g-bump