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

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https://hg.mozilla.org/integration/gaia-central/rev/0e90f6962a39
Author: Ricky Chien <ricky060709@gmail.com>
Desc: Merge pull request #26813 from RickyChien/bug-1021567

Bug 1021567 - Coverage threshold check in test agent file watcher r=@julienw

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https://hg.mozilla.org/integration/gaia-central/rev/408b9a80934b
Author: Ricky Chien <ricky060709@gmail.com>
Desc: Bug 1021567 - Coverage threshold check in test agent file watcher
Bumping manifests a=b2g-bump