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

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https://hg.mozilla.org/integration/gaia-central/rev/34d270e5530d
Author: albertopq <albert.pastor@gmail.com>
Desc: Merge pull request #26959 from albertopq/1111799-SHB-landscape

Bug 1111799 - Using appopened on the stack_manager r=etienne +autolander

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https://hg.mozilla.org/integration/gaia-central/rev/388b4b7eea64
Author: albertopq <albert.pastor@gmail.com>
Desc: Bug 1111799 - Using appopened on the stack_manager
Bumping manifests a=b2g-bump