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

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https://hg.mozilla.org/integration/gaia-central/rev/5c8b55b95dd9
Author: gitmai <mri@tid.es>
Desc: Merge pull request #16735 from gitmai/bug-858017-final-patch

Bug 858017 - [COST CONTROL] Use Gecko native support for data usage alar...
r=salva

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https://hg.mozilla.org/integration/gaia-central/rev/3d98ab3248df
Author: mai <mri@tid.es>
Desc: Bug 858017 - [COST CONTROL] Use Gecko native support for data usage alarms provided by NetworkStats API 2.0
Bumping manifests a=b2g-bump