The retryable writes spec should test that a client created with retryWrites=False does not retry writes.

This was noticed while reviewing WRITING-3546. Me:

Is there any retryableWrites test that a write fails and does not retry after one retryable error when retryWrites=False?

Jeremy:

I don't believe there were any tests for that behavior previously, as all tests that I see include clientOptions for retryWrites=true. I don't think this needs to go into this CR, but perhaps make a ticket to add a test for that down the line.