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

========

https://hg.mozilla.org/integration/gaia-central/rev/8462cee7d053
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 967516 - Enable DEVICE_DEBUG by default for non production builds r=ochameau"

This reverts commit 2cf552888bf0f2bfe8a6c7939f2cef5e57dbfcf1.
Bumping manifests a=b2g-bump