Bumping gaia.json for 1 gaia-central revision(s) a=NPOTB

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https://hg.mozilla.org/integration/gaia-central/rev/28971bc4c813
Author: Ghislain 'Aus' Lacroix <aus@mozilla.com>
Desc: Revert "Merge pull request #12323 from nullaus/891724-supportcontactcustomization"

This reverts commit dce497b5cf19183f51a867334dd0524c816493dc, reversing
changes made to 432a79aedb558d998ea88c04d43427a2082a67ee.