Refactor provisioning unit tests

There was some confusion about which tests loaded a cert and
which ones just used a cert. This distinction is important
when testing devices with a baked-in-cert.

Merged from https://widevine-internal-review.googlesource.com/183333

Change-Id: I3c2b119c3355b3a9190799637ff0860b6153b35b

libwvdrmengine/oemcrypto/test/oemcrypto_license_test.h

@@ -96,8 +96,6 @@ class OEMCryptoSessionTests : public OEMCryptoClientTest {
   }
 };
 
-class OEMCryptoSessionTestKeyboxTest : public OEMCryptoSessionTests {};
-
 // This class is for testing a single license with the default API version
 // of 16.
 class OEMCryptoLicenseTestAPI16 : public OEMCryptoSessionTests {
@@ -411,4 +409,4 @@ class OEMCryptoRefreshTestAPI16 : public OEMCryptoRefreshTest {};
 
 }  // namespace wvoec
 
-#endif  // CDM_OEMCRYPTO_LICENSE_TEST_
+#endif  // CDM_OEMCRYPTO_LICENSE_TEST_