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

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https://hg.mozilla.org/integration/gaia-central/rev/4d2b286ac818
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Revert "Bug 993188 - Clean up mozL10n.ready. r=gandalf"

This is breaking the callscreen app.

This reverts commit a96aeea2798dd3242b80e83d3b61a6896c71de9e.
Bumping manifests a=b2g-bump