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

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https://hg.mozilla.org/integration/gaia-central/rev/8e15f9d86165
Author: Albert <alberto.crespellperez@telefonica.com>
Desc: Merge pull request #21832 from acperez/bug-1037391

Bug 1037391 - Origin in manifest is ignored at build time. r=yurenju

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https://hg.mozilla.org/integration/gaia-central/rev/a0d2f8f34d84
Author: Albert <alberto.crespellperez@telefonica.com>
Desc: Bug 1037391 - Origin in manifest is ignored at build time. r=yurenju
Bumping manifests a=b2g-bump