Use GTEST_SKIP for non keybox devices

Bug: 251240681
Merged from https://widevine-internal-review.googlesource.com/179090

Change-Id: I8c539bfbccde7f22fb732951a95715935935858f

libwvdrmengine/oemcrypto/test/oemcrypto_license_test.cpp

@@ -85,6 +85,9 @@ void TestMaxKeys(SessionUtil* util, size_t num_keys_per_session) {
 }
 
 TEST_F(OEMCryptoSessionTestKeyboxTest, TestKeyboxIsValid) {
+  if (global_features.provisioning_method != OEMCrypto_Keybox) {
+    GTEST_SKIP() << "Test for Prov 2.0 devices only.";
+  }
   ASSERT_EQ(OEMCrypto_SUCCESS, OEMCrypto_IsKeyboxValid());
 }