NXCM-5067: Setting LDAP connection stuff in JVM props

Setting the Sun JNDI default implementation related properties.

Also, removing the dead code, as according to Sun documentation, the pooling might be set *only by system properties* (unlike putting key/values in env map as done here), *affects globally all contexts* (unlike code here expected to set per context).

Still, setter for polling left (and does nop), to adhere javadoc comments and to retain API compatibility.