See:

• https://github.com/mongodb/specifications/pull/563#discussion_r291763530
• https://github.com/mongodb/specifications/pull/563#discussion_r291763695

jeff.yemin believes there is little value in testing that $out does not support a linearizable read concern, as we are mainly testing server behavior. Likewise, there is not much value in asserting that an invalid read concern level results in a server error.

The only driver behavior being tested here is that the read concern level is passed as-is to the server. I intend to exclude these tests from the $merge tests (SPEC-1289) and would propose we delete the existing $out tests.