Bumping gaia.json for 1 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/856839e6554e
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Revert "Bug 946724 - [e.me] Collection suggestions for unsupported languages should show English suggestions [r=ranbena]"

This reverts commit acfc61da7dd2fca23db98295e695227309146c0b.