Explicitly set generate_hashtree: false

Non-updatable APEXes are going to be only present on a dm-verity
protected read-only partition. For such APEXes there is no need in
embedding a hashtree.

This is a no-op change in preparation of switching default value of
generate_hashtree to true.

Bug: 190621617
Test: m
Change-Id: I5fc70f2dc65bd50ecbf7eecb7ab2c0d5795d3331
diff --git a/apex/Android.bp b/apex/Android.bp
index 958c872..602f95f 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -23,6 +23,7 @@
     certificate: ":com.android.vndk.current.certificate",
     file_contexts: ":com.android.vndk-file_contexts",
     updatable: false,
+    generate_hashtree: false,
 }
 
 override_apex {