Test: Protected VM fails if images are signed by unknown

Arrange:
- prepare VM images signed with a test key
Act:
- start a protected VM
Assert:
- a boot process fails due to pubkey mismatch between pvmfw and
  bootloader

Bug: 218934597
Test: atest MicrodroidHostTestCases
Change-Id: I05755ddf32839ef531ca9a11b2939bbc251ff1fb
diff --git a/apex/Android.bp b/apex/Android.bp
index 25cd480..d12b27b 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -142,11 +142,16 @@
     ],
     data: [
         ":com.android.virt",
-        "test.com.android.virt.pem",
+        ":test.com.android.virt.pem",
     ],
     test_suites: ["general-tests"],
 }
 
+filegroup {
+    name: "test.com.android.virt.pem",
+    srcs: ["test.com.android.virt.pem"],
+}
+
 // custom tool to replace bytes in a file
 python_binary_host {
     name: "replace_bytes",