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

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https://hg.mozilla.org/integration/gaia-central/rev/feee488a651b
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #13054 from timdream/reverse-dnt-value

Bug 914407 - Correct the Do Not Track header values, r=arthurcc

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https://hg.mozilla.org/integration/gaia-central/rev/a3c830c358d1
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 914407 - Correct the Do Not Track header values