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

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https://hg.mozilla.org/integration/gaia-central/rev/bc7f52f44932
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #12776 from lightsofapollo/revert-

Revert "Merge pull request #12769 from gtorodelvalle/contacts-bug-924903...

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https://hg.mozilla.org/integration/gaia-central/rev/a904c6b34d1e
Author: James Lal <james@lightsofapollo.com>
Desc: Revert "Merge pull request #12769 from gtorodelvalle/contacts-bug-924903-custom-tag"

This reverts commit a2932738a6c05382e0f17284a3d24542439c9afe, reversing
changes made to 7f240f2da3178b275315790585396629dbe2d756.