Add default config to optimize LDAP group lookup

cacheManager = org.apache.shiro.cache.MemoryConstrainedCacheManager
securityManager.cacheManager = $cacheManager

<topology>
    <gateway>
        <provider>
            <role>authentication</role>
            <name>ShiroProvider</name>
            ...
            <param>
                <name>main.cacheManager</name>
                <value>org.apache.shiro.cache.MemoryConstrainedCacheManager</value>
	    </param>
            <param>
                <name>main.securityManager.cacheManager</name>
                <value>$cacheManager</value>
            </param>
            ....
        </provider>
        ....
    </gateway>
    ...
</topology>