Use APK CtsShim prebuilts for flattened apex.

Fix: 158036322
Test: built flame-userdebug with m OVERRIDE_TARGET_FLATTEN_APEX=true, ran
atest CtsAppSecurityHostTestCases:android.appsecurity.cts.PrivilegedUpdateTests#testDisableUpdatedSystemApp
and verified that the cts shim apex is not installed

Change-Id: Icc52500cfc0a555e11d1a467b2da0649c7f5d31f
Merged-In: Icc52500cfc0a555e11d1a467b2da0649c7f5d31f
(cherry picked from commit c9a786e5f77a5c06da6c07f718e4a7619a75d9e6)
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index c074807..1742bce 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -51,7 +51,6 @@
     charger \
     cmd \
     com.android.adbd \
-    com.android.apex.cts.shim.v1 \
     com.android.conscrypt \
     com.android.extservices \
     com.android.i18n \
@@ -71,6 +70,8 @@
     ContactsProvider \
     content \
     crash_dump \
+    CtsShimPrebuilt \
+    CtsShimPrivPrebuilt \
     debuggerd\
     device_config \
     dmctl \
diff --git a/target/product/updatable_apex.mk b/target/product/updatable_apex.mk
index e5a647c..a84a0d2 100644
--- a/target/product/updatable_apex.mk
+++ b/target/product/updatable_apex.mk
@@ -17,6 +17,8 @@
 # Inherit this when the target needs to support updating APEXes
 
 ifneq ($(OVERRIDE_TARGET_FLATTEN_APEX),true)
+  # com.android.apex.cts.shim.v1_prebuilt overrides CtsShimPrebuilt
+  # and CtsShimPrivPrebuilt since they are packaged inside the APEX.
   PRODUCT_PACKAGES += com.android.apex.cts.shim.v1_prebuilt
   PRODUCT_PROPERTY_OVERRIDES := ro.apex.updatable=true
   TARGET_FLATTEN_APEX := false