Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/5574ba38d871
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 1016816 - [CostControl] Update to use gaia-header"

This reverts commit 73c4a88e49f80ae5fa174488a5af1347e6c1fde0.

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https://hg.mozilla.org/integration/gaia-central/rev/392331c8cf24
Author: Wilson Page <wilsonpage@me.com>
Desc: Merge pull request #22488 from wilsonpage/1016816

Bug 1016816 - [CostControl] Update to use gaia-header

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https://hg.mozilla.org/integration/gaia-central/rev/efe66b706dc7
Author: Yan Or <yor@mozilla.com>
Desc: Bug 1016816 - [CostControl] Update to use gaia-header

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "6b7be0fb800b102766edbd30d976da99fcf69533", 
+    "revision": "5574ba38d87128480049442edfa2c056404b45f2", 
     "repo_path": "/integration/gaia-central"
 }