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

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https://hg.mozilla.org/integration/gaia-central/rev/5a7bbada29f6
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #21309 from jrburke/bug1033628-email-search-overlap

Bug 1033628 - [B2G][2.0][l10n][Email]Tamil: Searching email in Tamil causes the window to shift off screen r=mcav

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https://hg.mozilla.org/integration/gaia-central/rev/4b2db27b77f1
Author: jrburke <jrburke@gmail.com>
Desc: Bug 1033628 - [B2G][2.0][l10n][Email]Tamil: Searching email in Tamil causes the window to shift off screen

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https://hg.mozilla.org/integration/gaia-central/rev/7c7041058dbd
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Merge pull request #20760 from eeejay/bug-1027740

Bug 1027740 - Make accessibility UI test failures more verbose. r=jgriffin

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https://hg.mozilla.org/integration/gaia-central/rev/8e887f52284b
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 1027740 - Make accessibility UI test failures more verbose
Bumping manifests a=b2g-bump