Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-2_1/rev/1b51e3201abd
Author: KWierso <kwierso@gmail.com>
Desc: Merge pull request #26344 from mikehenrty/lissyx-with-test-skip

Lissyx with test skip a=bajaj

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https://hg.mozilla.org/integration/gaia-2_1/rev/98405af0bbeb
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 1088224 - Skipping notification overwrite test until gecko patch lands

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https://hg.mozilla.org/integration/gaia-2_1/rev/786273dc1462
Author: Alexandre Lissy <lissyx+github@lissyx.dyndns.org>
Desc: Bug 1088224 - Ensuring resent notification do not overwrite new ones r=mherentty
Bumping manifests a=b2g-bump