Revert "KNOX-459 - added null checks to the closing of resultEnums to avoid NPEs"

This reverts commit d96d8b5b9e4a8e1aef1c3e8296431dfb39346040.

Accidentally committed - reverting.
Revert "KNOX-459 - fixed LDAP connection leaks in KnoxLdapRealm"

This reverts commit 0a41c3948447990917b88e104dd70a5a42f18fd3.

Accidentally committed - reverting.