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

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https://hg.mozilla.org/integration/gaia-central/rev/727c97afb2a5
Author: gitmai <mri@tid.es>
Desc: Merge pull request #20546 from gitmai/bug-837678-CC-perf-test

Bug 837678 - [cost control] Implement new startup loading events
r=salva

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https://hg.mozilla.org/integration/gaia-central/rev/1c34c43198ca
Author: mai <mri@tid.es>
Desc: Bug 837678 - [cost control] Implement new startup loading events
Bumping manifests a=b2g-bump