Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/ce0bc0435690
Author: Staś Małolepszy <stas@mozilla.com>
Desc: Merge pull request #18643 from stasm/1000866-sms-ready-once

Bug 1000866 - Clean up bootstrap mozL10n API use in SMS. r=julienw

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https://hg.mozilla.org/integration/gaia-central/rev/863c44882d83
Author: Staś Małolepszy <stas@mozilla.com>
Desc: Bug 1000866 - Clean up bootstrap mozL10n API use in SMS. r=julienw

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https://hg.mozilla.org/integration/gaia-central/rev/2397478d8773
Author: Jan Keromnes <janx@linux.com>
Desc: Merge pull request #18880 from paulrouget/bug942756

Bug 942756 - Unify debugger server startup: dbg-server.jsm should be imported in tests. r=me

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https://hg.mozilla.org/integration/gaia-central/rev/d67ad2c5585f
Author: Paul Rouget <me@paulrouget.com>
Desc: Bug 942756 - Unify debugger server startup: dbg-server.jsm should be imported in tests. r=janx
Bumping manifests a=b2g-bump