Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/dd49fabb5c9d
Author: Albert <acperez@tid.es>
Desc: Merge pull request #11833 from acperez/bug-904005

Bug 904005 - Generate internal json conf file for remote custom single variant apps at build time. r=yurenju

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https://hg.mozilla.org/integration/gaia-central/rev/218f79ebbb53
Author: Albert <acperez@tid.es>
Desc: Bug 904005 - Generate internal json conf file for remote custom single variant apps at build time. r=yurenju