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

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https://hg.mozilla.org/integration/gaia-central/rev/8a69414eaca6
Author: KWierso <kwierso@gmail.com>
Desc: Revert "Merge pull request #25420 from gaye/bug-821604" for Gu test failures

This reverts commit 3b98c6a903e79ea16a51832fa4be23f817ab5829, reversing
changes made to 4ee0a68bc71b00808313b21ebd7c3b6a60e98d14.
Bumping manifests a=b2g-bump