DDS15 — get_discovered_participant_data() should return BAD_PARAMETER instead of PRECONDITION_NOT_MET

This issue has to do with the proper code when the function
get_discovered_participant_data gets passed an invalid handle.

This function is analogous to get_matched_subscription_data() and get_matched_publication_data() except that that it retrieves information on the matching participant instead of the matching endpoint. All these functions take a handle as an input that refers to the "matching" entity for which information is
being retrieved.

Prior to version 1.2 get_matched_subscription_data() was returning PRECONDITION_NOT_MET and get_matched_publication_data BAD_PARAMETER.
Returning BAD_PARAMETER seemed more appropriate so in version 1.2 (OMG issue 9500) we updated get_matched_subscription_data to also return BAD_PARAMETER.

However get_discovered_participant_data() was not updated as part of is still returning PRECONDITION_NOT_MET.

Therefore get_discovered_participant_data() should be updated to also return BAD_PARAMETER when an invalid handle is passed.