Bumping gaia.json for 2 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/c4c6143d1253
Author: Florin Strugariu <bebef_1987@yahoo.com>
Desc: Merge pull request #14031 from bobsilverberg/bug932753-1.2

Bug 932753 - Update test_settings_do_not_track to use new Gecko pref helper methods

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https://hg.mozilla.org/integration/gaia-1_2/rev/f9b95089315b
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Bug 932753 - Update test_settings_do_not_track to use new Gecko pref helper methods