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

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https://hg.mozilla.org/integration/gaia-central/rev/5fccd54fb65b
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Revert "Merge pull request #12212 from gaye/bumpt-marionette-client"

This reverts commit a4255258e5ee8123602f4d307c9057ae327c2190, reversing
changes made to 3218122421bdab8c1b5b631ad789fd035d5a81eb.

I'm backing this on speculation that this is making everything time out