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

========

https://hg.mozilla.org/integration/gaia-central/rev/bf43989425f4
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Revert "Merge pull request #21397 from Rik/update-xulrunner-1034565"

This reverts commit 51ce45b25eaf9cdba330aa11b77eb9dae475e98a, reversing
changes made to d681dcfa20625fb81582fae9e2b2d91ec3eb534b.
Bumping manifests a=b2g-bump