Make packages/modules/Virtualization tests available to the platform

Soong was accidentally allowing a corner case where modules that
were not supposed to be available to the platform (due to
apex_available being set to an apex and not including
"//apex_available:platform") were being made available to the
platform as long as no apex modules depended on them.  Move the
apex_available: ["com.android.virt"] from the defaults modules
to the rust_library modules so that it doesn't apply to the
rust_test modules.

Bug: 394664568
Test: compare out/soong/installs-${TARGET_PRODUCT}.mk
Change-Id: Idff0deb6063ad0bc4ce4a95c43f6fb4d19e57260
diff --git a/libs/libservice_vm_requests/Android.bp b/libs/libservice_vm_requests/Android.bp
index d87b087..4a575b2 100644
--- a/libs/libservice_vm_requests/Android.bp
+++ b/libs/libservice_vm_requests/Android.bp
@@ -9,9 +9,6 @@
     defaults: ["avf_build_flags_rust"],
     srcs: ["src/lib.rs"],
     prefer_rlib: true,
-    apex_available: [
-        "com.android.virt",
-    ],
     no_stdlibs: true,
     stdlibs: [
         "libcore.rust_sysroot",
@@ -37,6 +34,9 @@
 rust_library_rlib {
     name: "libservice_vm_requests_nostd",
     defaults: ["libservice_vm_requests_nostd_defaults"],
+    apex_available: [
+        "com.android.virt",
+    ],
 }
 
 rust_test {