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

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https://hg.mozilla.org/integration/gaia-central/rev/5449cb5b262e
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Revert "Merge pull request #14667 from mcav/utf7"

This reverts commit cfa88581f0bdaa3d4b7a3773ae87edc55260a2ab, reversing
changes made to b44a75862ebcb651381eabc9c3a3b203d76d63bf.

This is breaking 6 integration tests