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

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https://hg.mozilla.org/integration/gaia-central/rev/fb502dc0e034
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Revert "Merge pull request #26189 from albertopq/1074332-icons-toggle"

This reverts commit 8654a14cd4a790484603fded2566367eca6cbeb6, reversing
changes made to efeabc1b3435eeea619734051f144a521cf483f8.
Bumping manifests a=b2g-bump