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

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https://hg.mozilla.org/integration/gaia-central/rev/609201aba1a4
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #12379 from lightsofapollo/backout-incremental-commits

Revert "Merge pull request #10981 from ganesh7/bug_819628"

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https://hg.mozilla.org/integration/gaia-central/rev/c5123c3ba5cd
Author: James Lal <james@lightsofapollo.com>
Desc: Revert "Merge pull request #10981 from ganesh7/bug_819628"

This reverts commit 8a91b987b57e01d03eded32c33a68595bd0949cb, reversing
changes made to dfff18a59944e64f527030ff71223f30d8f45840.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "15e0ed73da280245c3cee6765fd257d31e2dee06", 
+    "revision": "609201aba1a427e086906301c1fc86e586499529", 
     "repo_path": "/integration/gaia-central"
 }