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

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https://hg.mozilla.org/integration/gaia-central/rev/dd5811658293
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #24223 from daleharvey/1067573

Bug 1067573 - Add test to ensure default preloaded top sites show.

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https://hg.mozilla.org/integration/gaia-central/rev/18411172c4ac
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 1067573 - Add test to ensure default preloaded top sites show. r=kgrandon
Bumping manifests a=b2g-bump