Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/3451c5dbd0bf
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #10951 from KevinGrandon/bug_893188_fix_system_messages

Bug 893188 - Update system message manager r=vingtetun

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https://hg.mozilla.org/integration/gaia-central/rev/d5d6294ffcef
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 893188 - Update system message manager