Use GTEST_SKIP for session tests

Bug: 251240681
Merged from https://widevine-internal-review.googlesource.com/180010

Change-Id: I39e5c0365a5e0c2ddf62e6f68426f6baa3ddd1a1

libwvdrmengine/cdm/core/test/cdm_session_unittest.cpp

@@ -12,6 +12,7 @@
 #include "cdm_usage_table.h"
 #include "crypto_key.h"
 #include "crypto_wrapped_key.h"
+#include "oec_device_features.h"
 #include "properties.h"
 #include "service_certificate.h"
 #include "string_conversions.h"
@@ -215,6 +216,10 @@ class CdmSessionTest : public WvCdmTestBase {
  protected:
   void SetUp() override {
     WvCdmTestBase::SetUp();
+    if (wvoec::global_features.derive_key_method ==
+        wvoec::DeviceFeatures::NO_METHOD) {
+      GTEST_SKIP() << "Test for devices that can derive session keys only.";
+    }
     metrics_ = std::make_shared<metrics::SessionMetrics>();
     cdm_session_.reset(new CdmSession(nullptr, metrics_));
     // Inject testing mocks.