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

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https://hg.mozilla.org/integration/gaia-central/rev/8435abd6a8ed
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #21429 from gasolin/issue-951538

Bug 951538 - [Settings] Move Reset option up one level, r=arthur

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https://hg.mozilla.org/integration/gaia-central/rev/e8307f2edfb6
Author: gasolin <gasolin@gmail.com>
Desc: Bug 951538 - [Settings] Move Reset option up one level
Bumping manifests a=b2g-bump