Move logic to disable flattening in unbundled app mode from Soong to
make.

Avoids TARGET_FLATTEN_APEX lying about it, so we can trust it in
scripts, e.g. in art/build/apex/runtests.sh.

Test: banchan com.android.art; art/build/apex/runtests.sh
Bug: 179900989
Change-Id: I5361957c448e61634689968424450420479f6111
diff --git a/apex/apex.go b/apex/apex.go
index 3448327..926085b 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -2020,7 +2020,7 @@
 	a.filesInfo = filesInfo
 
 	// Set suffix and primaryApexType depending on the ApexType
-	buildFlattenedAsDefault := ctx.Config().FlattenApex() && !ctx.Config().UnbundledBuildApps()
+	buildFlattenedAsDefault := ctx.Config().FlattenApex()
 	switch a.properties.ApexType {
 	case imageApex:
 		if buildFlattenedAsDefault {