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

========

https://hg.mozilla.org/integration/gaia-central/rev/25b8ce8615e9
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #20154 from benfrancis/1021777

Bug 1021777 - Set multiple search engines by default r=daleharvey

========

https://hg.mozilla.org/integration/gaia-central/rev/fb58dad17e25
Author: Ben Francis <ben@tola.me.uk>
Desc: Bug 1021777 - Set multiple search engines by default
Bumping manifests a=b2g-bump