LDAP paged results are not only used/needed with MS AD. The feature can be used with any LDAP server that supports that feature (which is quite useful if you deal with a large number of users, as it alleviates the load on the LDAP server for large queries).
That's why Moodle shows the message, so you know that you could benefit from the feature if you complied with the requirements. It's neither a warning nor an error, just an informative message and everything should work as usual. I.e., if it worked before this feature went into Moodle, it will work now aswell. And if you had trouble before with large user bases (as was notably the case with MS AD, but again this is not specific to MS AD, as all LDAP servers have limits on the number of "objects" they will return) it will be able to work now, provided you fulfill the conditions to enable the feature.
Answering your specific question (how do I get rid of it?), there's no way to do it unless you edit the code (or you install a suitable PHP version and configure the LDAP plugin to use version 3 of the protocol )