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

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https://hg.mozilla.org/integration/gaia-central/rev/2838c1b561aa
Author: Fernando Campo <fernando.campo@telefonica.com>
Desc: Merge pull request #19159 from fcampo/contacts-edit-name-behind-title-994572

Bug 994572 - Name behind title when edit contact (r=jmcf)

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https://hg.mozilla.org/integration/gaia-central/rev/751ae548d159
Author: Fernando Campo <fernando.campo@telefonica.com>
Desc: Bug 994572 - Name behind title when edit contact
Bumping manifests a=b2g-bump