Delete the last vestiges of ntoreturn

We need to remove a few things that were introduced in SERVER-57461 once v6.0 is cut.

• Delete jstests/core/find_with_ntoreturn_fails.js.
• Remove ntoreturn from the FindCommandRequest IDL.
• Delete translation logic in find_cmd.cpp `translateNtoReturnToLimitOrBatchSize()`.