[attestation] Rename service_vm/client_apk to test_apk

Since this APK is only for manual testing currently. Renaming it
to avoid any confusion.

Test: m ServiceVmClientTestApp
Change-Id: Iba04add3a1adb826df4215b5f45d4307ecc7d4fb
diff --git a/vm_payload/Android.bp b/vm_payload/Android.bp
index d2ac7ee..b5322a8 100644
--- a/vm_payload/Android.bp
+++ b/vm_payload/Android.bp
@@ -35,7 +35,7 @@
     apex_available: ["com.android.compos"],
     visibility: [
         "//packages/modules/Virtualization/compos",
-        "//packages/modules/Virtualization/service_vm/client_apk",
+        "//packages/modules/Virtualization/service_vm/test_apk",
     ],
     shared_libs: [
         "libvm_payload#current",