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

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https://hg.mozilla.org/integration/gaia-central/rev/4a07bce4cd6b
Author: Jonathan Griffin <jgriffin@mozilla.com>
Desc: Bug 1059448 - Depend on marionette_client 0.8.3 and bump version of gaiatest to 0.27, r=zac

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https://hg.mozilla.org/integration/gaia-central/rev/526b33fd4e06
Author: Guillaume C. Marty <gmarty@users.noreply.github.com>
Desc: Merge pull request #23211 from gmarty/Bug-1056965-Status-Bar-Layout-Spacing-Adjustments

Bug 1056965 - [Status Bar] Layout/Spacing Adjustments

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https://hg.mozilla.org/integration/gaia-central/rev/4304695ff974
Author: Guillaume Marty <edo999@gmail.com>
Desc: Bug 1056965 - [Status Bar] Layout/Spacing Adjustments

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https://hg.mozilla.org/integration/gaia-central/rev/02de44fecdbd
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Bug 1059678 - Provide a sensible default timeout for wait_for_b2g_ready. r=zcampbell
Bumping manifests a=b2g-bump