Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/ce6f35e577ca
Author: Andrew Halberstadt <halbersa@gmail.com>
Desc: Merge pull request #20458 from ahal/gu-determinism

Bug 1023198 - Sort Gu tests after os.walk for determinism, jgriffin

========

https://hg.mozilla.org/integration/gaia-central/rev/624dd9c65fd7
Author: Andrew Halberstadt <halbersa@gmail.com>
Desc: Bug 1023198 - Sort Gu tests after os.walk for determinism, jgriffin
Bumping manifests a=b2g-bump