Cleanup Android.bp:framework-virtualization

There are a bunch of variables that are already set in the
framework-module-defaults, so there is no need to duplicate them.

Also disable the JavaApiUsedByMainlineModule check, since we are not an
updatable module we don't need it, and it's quite spammy.

As a side effect of this change our tests & demo apks need to compile
against framework-virtualization.impl library (which includes the hidden
APIs). Once the APIs are promoted to @SystemApi we can change the tests
to compile against framework-virtualization (which contains the API
stubs).

Bug: 243512044
Test: presubmit
Change-Id: Ib614d266f7a9cb8517afccd4feb737068b51fb20
diff --git a/demo/Android.bp b/demo/Android.bp
index 5241e25..2b234a6 100644
--- a/demo/Android.bp
+++ b/demo/Android.bp
@@ -13,7 +13,10 @@
         "com.google.android.material_material",
     ],
     libs: [
-        "framework-virtualization",
+        // We need to compile against the .impl library which includes the hidden
+        // APIs. Once the APIs are promoted to @SystemApi we can switch to
+        // framework-virtualization, which contains API stubs.
+        "framework-virtualization.impl",
     ],
     jni_libs: ["MicrodroidTestNativeLib"],
     platform_apis: true,