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

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https://hg.mozilla.org/integration/gaia-central/rev/21a79199c886
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #26683 from crh0716/1109387

Bug 1109387 - Fix the alphabetical sorting r=eragonj

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https://hg.mozilla.org/integration/gaia-central/rev/b9801f0cf235
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 1109387 - Fix the alphabetical sorting
Bumping manifests a=b2g-bump