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

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https://hg.mozilla.org/integration/gaia-central/rev/90860a00da53
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #18579 from bebef1987/cell_data

Bug 996645 - Data Connection switch is not waiting for the Connection to...

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https://hg.mozilla.org/integration/gaia-central/rev/8dc5000b2030
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 996645 - Data Connection switch is not waiting for the Connection to be "active" before switching to the the on state
Bumping manifests a=b2g-bump