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
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index 9daa8a4..6591118 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.appsearch \
     com.android.conscrypt \
     com.android.cronet \
@@ -72,6 +71,8 @@
     com.android.wifi \
     ContactsProvider \
     content \
+    CtsShimPrebuilt \
+    CtsShimPrivPrebuilt \
     debuggerd\
     device_config \
     dmctl \