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

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https://hg.mozilla.org/integration/gaia-central/rev/d8cea8734611
Author: George <georgeiscoming@gmail.com>
Desc: Merge pull request #16985 from cctuan/971437

Bug 971437 - Unify GAIA_DIR/customization and GAIA_DIR/build/test/resour...

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https://hg.mozilla.org/integration/gaia-central/rev/7e2435c729a4
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 971437 - Unify GAIA_DIR/customization and GAIA_DIR/build/test/resource/distribution_test
Bumping manifests a=b2g-bump