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

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https://hg.mozilla.org/integration/gaia-central/rev/5143c5edf9df
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 966215 - Allow make test-integration to specify TEST_FILES. r=gaye

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https://hg.mozilla.org/integration/gaia-central/rev/ed9bb3f662e9
Author: Kyle Machulis <kyle@nonpolynomial.com>
Desc: Merge pull request #16097 from qdot/969587-variant-with-no-icc

Bug 969587 - Run variant customization with no icc

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https://hg.mozilla.org/integration/gaia-central/rev/7a8134fdef11
Author: Kyle Machulis <kyle@nonpolynomial.com>
Desc: Bug 969587 - Integration tests for FTU variant customization

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https://hg.mozilla.org/integration/gaia-central/rev/acc8e5f9225e
Author: Kyle Machulis <kyle@nonpolynomial.com>
Desc: Bug 969587 - Make customization run without ICCHelper present
Bumping manifests a=b2g-bump