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

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https://hg.mozilla.org/integration/gaia-central/rev/9e900ea5ab33
Author: Ryan VanderMeulen <ryanvm@gmail.com>
Desc: Merge pull request #24791 from rjmackay/bug-1062798-settings-app-json-loading

Bug 1062798 - Replace custom JSON loaders with LazyLoader.getJSON in Settings App

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https://hg.mozilla.org/integration/gaia-central/rev/29e1ba8d5c8d
Author: Robbie Mackay <rm@robbiemackay.com>
Desc: Bug 1062798 - Replace custom JSON loaders with LazyLoader.getJSON in SettingsApp

Replace various custom JSON loaders in SettingsApp with LazyLoader.getJSON.
Refactor code to handle promises where needed, and update tests to match.

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "f873a6c302e423960b4ad9dc3c240e33f39bf76e", 
+    "revision": "9e900ea5ab3306f2b0622a9d0b4a5f42c2bca70c", 
     "repo_path": "/integration/gaia-central"
 }