Bug 2011886 - Set isolation strategy to ISOLATE_NONE r=kaya,tcampbell

This is set in all builds except nightly

Pull request: #39

Author: pollym

mobile/android/fenix/app/nimbus.fml.yaml

@@ -449,7 +449,14 @@ features:
           process. "2" means "isolate high value", Android-specific setting to only isolate sites
           considered "high value".
         type: Int
-        default: 2
+        default: 0
+    defaults:
+      - channel: nightly
+        value:
+          isolationStrategy: 2
+      - channel: developer
+        value:
+          isolationStrategy: 2
 
   suggest-shipped-domains:
     description: Feature that suggests domains from the shipped domain list.