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

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https://hg.mozilla.org/integration/gaia-central/rev/cf33bfa7452a
Author: Yuren Ju <yurenju@gmail.com>
Desc: Revert "Bug 897352 - [gaia build system] Transition to a build_stage for assembling apps"

This reverts commit 8126421998f0e1b0bf618f6788db7eabb26be0b8.
Bumping manifests a=b2g-bump