Make SSLClientSocketVersionTest.CTIsRequiredByExpectCT with partitioning

Currently, the test fails when all ExpectCT partitioning options is
enabled, because its call to AddExpectCT() uses an empty
NetworkIsolationKey, while its other calls use a specific transient key.
This CL fixes the test to pass in the same transient key.

This CL doesn't modify the test to enable ExpectCT partitioning, since
that has to be done before the TransportSecurityState is constructed.

Bug: 969893
Change-Id: Ie36e8d0fc8c10028f57925d393309dd3e1658faa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2595628Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837684}

net/socket/ssl_client_socket_unittest.cc

@@ -4391,7 +4391,7 @@ TEST_P(SSLClientSocketVersionTest, CTIsRequiredByExpectCT) {
   const base::Time expiry = current_time + base::TimeDelta::FromSeconds(1000);
   transport_security_state_->AddExpectCT(
       host_port_pair().host(), expiry, true /* enforce */,
-      GURL("https://example-report.test"), NetworkIsolationKey());
+      GURL("https://example-report.test"), network_isolation_key);
   MockExpectCTReporter reporter;
   transport_security_state_->SetExpectCTReporter(&reporter);