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

========

https://hg.mozilla.org/integration/gaia-central/rev/2632cc25a7cc
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #14992 from gaye/noflake

Allow gaia_ui_tests to fail on travis

========

https://hg.mozilla.org/integration/gaia-central/rev/b8ed1597c7e9
Author: Gareth Aye <gaye@mozilla.com>
Desc: Allow gaia_ui_tests to fail on travis