Cleanup work around for JDK's SSLEngine not throwing SSLHandshakeException

[Scottmitch]

Expected behavior

When a TLS/SSL handshake is failed it is expected that the SSLEngine will throw a SSLHandshakeException. We have added some work arounds in unit tests to allow for non SSLHandshakeException so the unit tests will pass. We should remove these workarounds after the issue is addressed.

Actual behavior

The JDK's implementation of SSLEngine does not always do this.

Steps to reproduce

Run JdkOpenSslEngineInteroptTest and JdkOpenSslEngineInteroptTest but also remove the mySetupMutualAuthServerIsValidServerException and mySetupMutualAuthServerIsValidClientException methods.

Netty version

4.1.9

JVM version (e.g. java -version)

java version "1.8.0_112"
Java(TM) SE Runtime Environment (build 1.8.0_112-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.112-b16, mixed mode)

OS version (e.g. uname -a)

macOS Sierra 10.12.3

[Scottmitch]

Related #6421

[Scottmitch]

@normanmaurer - please link the JDK issue here when it is created.