Do not fall back to L3 if L1 has test keybox

ag/26105061 accidentally reverted some of these changes so I am pushing
up another patch to add them back in.

[ Merged of go/wvgerrit/186370 ]

CDM by default allows test keybox from device side.

Bug: 299987160
Bug: 301669353
Change-Id: I6acf93c78f76a13f2c4539aabfd0262670b54c48

libwvdrmengine/cdm/core/test/test_base.cpp

@@ -205,7 +205,6 @@ TestCryptoSession::TestCryptoSession(metrics::CryptoMetrics* crypto_metrics,
 
 void TestCryptoSession::MaybeInstallTestKeybox() {
   if (IsTestKeyboxNeeded()) {
-    CryptoSession::SetAllowTestKeybox(true);
     ReinitializeForTest();
     WvCdmTestBase::InstallTestRootOfTrust();
   }