This patch makes it so that both the classic engine and SBE obey the following semantics for the $_requestResumeToken and $_resumeAfter query options:

• For $_requestResumeToken, 'null' is returned as the resumeToken after scanning the last document in a collection (prior to this patch, SBE would return the record id of the last document).
• When a null RecordId is specified to $_resumeAfter, we raise a KeyNotFound error (prior to this patch, the classic engine would restart the scan from the beginning).

  Description of Linked Ticket

  When resuming from the last record in a collection, the classic engine returns resume token {"$recordId" : null} and SBE returns the last record.
  Resuming from {"$recordId" : null} in the classic record cycles back to the start of the collection and raises "KeyNotFound" error in SBE.