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

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https://hg.mozilla.org/integration/gaia-central/rev/78d735b50d94
Author: Sherman Chen <shamenchens@users.noreply.github.com>
Desc: Merge pull request #26219 from weilonge/STK_REFACTOR_for_master

Bug 1102185 - [FFOS2.0][Woodduck][STK]There has no terminal response when execute "setup call ->cancel"., r=frsela, r=arthurchen

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https://hg.mozilla.org/integration/gaia-central/rev/b4f846a93c42
Author: Sean Lee <weilonge@gmail.com>
Desc: Bug 1102185 - [FFOS2.0][Woodduck][STK]There has no terminal response when execute "setup call ->cancel".

1. Clear the event of onVisibilityChange when any option is clicked.
2. Redirect visibilityChange of Settings to System app. System app handles the event is a better strategy.
3. Add test case to handle on visibility change event from Settings app.
Bumping manifests a=b2g-bump