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

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https://hg.mozilla.org/integration/gaia-central/rev/073b3f973451
Author: Florin Strugariu <bebef_1987@yahoo.com>
Desc: Merge pull request #19243 from AndreiH/bug_1003175_master

Bug 1003175 - Investigate failure in test_cards_view_kill_apps_with_two_...

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https://hg.mozilla.org/integration/gaia-central/rev/757b37f5bcb4
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 1003175 - Investigate failure in test_cards_view_kill_apps_with_two_apps.py
Bumping manifests a=b2g-bump