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

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https://hg.mozilla.org/integration/gaia-central/rev/a75131f0d840
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #14600 from crdlc/bug-949351

Bug 949351 - [Download Manager] Remove workaround to avoid bug 944682

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https://hg.mozilla.org/integration/gaia-central/rev/e71c17134565
Author: crdlc <crdlc@tid.es>
Desc: Bug 949351 - [Download Manager] Remove workaround to avoid bug 944682