Hmm. Actually I tried to remove the pagedResultsControl from subsequent searches using the controlPagedResult($link_resource, 0, false, "") below.
But unfortunately this doesn't seem to work, setting the limit to 0 will include a pagedResultsControl with that size and the next search will indeed yield 0 results. :-(

Unfortunately I couldn't find a way to tell the ldap client library to remove the control for subsequent searches.
So it looks like using a high value as search limit will be our only option now.
However, I'd still prefer resetting it after the search, not before some next search operations.
So I'd still vote for removing this line here.