Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/ff9bea59dca3
Author: chirarobert <robert.chira@softvision.ro>
Desc: Merge pull request #20443 from zacc/bug_1021732

Bug 1021732 - Update test_privileged_app_contacts_prompt to match new pr...

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https://hg.mozilla.org/integration/gaia-central/rev/c656016378b7
Author: Zac <zcampbell@mozilla.com>
Desc: Bug 1021732 - Update test_privileged_app_contacts_prompt to match new prompt behaviour

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https://hg.mozilla.org/integration/gaia-central/rev/722a497fa58b
Author: chirarobert <robert.chira@softvision.ro>
Desc: Merge pull request #20444 from zacc/bug_1024516

Bug 1024516 - Update test_privileged_app_audio_prompt and video_prompt t...

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https://hg.mozilla.org/integration/gaia-central/rev/c1169bd52878
Author: Zac <zcampbell@mozilla.com>
Desc: Bug 1024516 - Update test_privileged_app_audio_prompt and video_prompt to match new prompt behaviour
Bumping manifests a=b2g-bump