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

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https://hg.mozilla.org/integration/gaia-central/rev/65a3ad901ad9
Author: Carsten Book -Tomcat- <cbook@mozilla.com>
Desc: Revert "Bug 935094 - [Download Manager] Download notifications" for breaking Gaia UI Tests

This reverts commit 55d5a661d0ffef0bd9db3405912ba0d5ce3ae339.