Remove @Ignore from SarTestCase

This test was ignored due to issues introduced by the security manager upgrade, as it now fails under the security manager due to checking being true by default.

The MBean server does an explicit check on the ProtectionDomain of the class, which is what causes the issue.

Caused by: java.security.AccessControlException: WFSM000001: Permission check failed (permission "("javax.management.MBeanTrustPermission" "register")" in code source "(vfs:/content/sar-example.sar <no signer certificates>)" of "null")