feat(NODE-6472): findOne and find no longer keep open cursors

[durran]

Description

Changes findOne to set options that will not require a cursor or a killCursors command. Updates find to not leave cursors open on the server when batch size and limit are equal.

What is changing?

• The find one operation now deprecates options for it specifically which are irrelevant.
• The find operation now sets batchSize to batchSize + 1 when the limit is equal to it.
• Syncs CRUD spec tests.

Is there new documentation needed for these changes?

API docs on the findOne options.

What is the motivation for this change?

NODE-6472

Release Highlight

collection.findOne() and collection.find() will no longer potentially leave open cursors on the server

The findOne command will now always set the limit option to 1 and singleBatch to true. The limit, noCursorResponse and batchSize options have also been deprecated, and the command will guarantee no more cursors can be orphaned and no killCursors command will be potentially executed.

find will now set limit to batchSize + 1 when both options were equal, to avoid leaving cursors open.

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[durran]

I made the decision here to do the options changes - creating a new find one operation was much more code and was suspiciously failing 6 tests in load balancer mode. This creating the cursor object works just fine and passes all tests, no killCursors is sent and the cursor on the server side always comes back with id 0.