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

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https://hg.mozilla.org/integration/gaia-central/rev/f5cb21cfe09c
Author: Fabrice Desré <fabrice@desre.org>
Desc: Merge pull request #25231 from clouserw/1083528

Bug 1083528 - Ship engineering builds with correct dev/stage Marketplaces r=fabrice

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https://hg.mozilla.org/integration/gaia-central/rev/9d2125c29f98
Author: Wil Clouser <clouserw@gmail.com>
Desc: Bug 1083528 - Ship engineering builds with correct dev/stage Marketplaces
Bumping manifests a=b2g-bump