fix(e2e-tests): remove pre-4.2 tests, explicitly allow certless connections MONGOSH-1592 (#1646)

We do not test against the 4.0 server anymore, so we can remove
the tests for that server version from our e2e test suite.

Also, add `--tlsAllowConnectionsWithoutCertificates` to account
for upcoming server changes that require this flag to be explicitly
set when connecting without a client certificate.

Author: addaleax