Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/5ba63adf96db
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #21178 from jmcanterafonseca/global_contacts

Bug 1026473 - [Contacts][Refactor] Implement the Global Contacts Datasto...

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https://hg.mozilla.org/integration/gaia-central/rev/c2e1ba6083c9
Author: José Manuel Cantera <jmcanterafonseca@gmail.com>
Desc: Bug 1026473 - [Contacts][Refactor] Implement the Global Contacts Datastore data management module

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https://hg.mozilla.org/integration/gaia-central/rev/ab6d7c9bef05
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21467 from KevinGrandon/bug_1035442_collection_tests_split

Bug 1035442 - Split up collections tests

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https://hg.mozilla.org/integration/gaia-central/rev/68ed72775f2b
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1035442 - Split up collections tests r=amirn
Bumping manifests a=b2g-bump