Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/4024e28dbc44
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Revert "Merge pull request #22001 from mikehenrty/bug-1038988-wallpaper-flatten"

This reverts commit 8abddb42a444dd165332e6642133932a04020b50, reversing
changes made to 90bb50d59cffda27e1bf035c9590a5f3062e4832.

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "3ebe8f47e643c99d535a875d088293df08999a83", 
+    "revision": "4024e28dbc44b11d3297378484c2474dcee425fa", 
     "repo_path": "/integration/gaia-central"
 }