Treat system_ext as system container

Bug: b/365135457
Test: m
Change-Id: Ic8fd60c0e1045f190b6608931ca1d65a784026f0

aconfig/aconfig_declarations.go

@@ -88,6 +88,13 @@ func (module *DeclarationsModule) DepsMutator(ctx android.BottomUpMutatorContext
 		ctx.PropertyErrorf("container", "missing container property")
 	}
 
+	// treating system_ext as system partition as we are combining them as one container
+	// TODO remove this logic once we start enforcing that system_ext cannot be specified as
+	// container in the container field.
+	if module.properties.Container == "system_ext" {
+		module.properties.Container = "system"
+	}
+
 	// Add a dependency on the aconfig_value_sets defined in
 	// RELEASE_ACONFIG_VALUE_SETS, and add any aconfig_values that
 	// match our package.