twister: pytest: fix duplicate log lines from pytest

The combination of pytest's `-s` (--capture=no) option and
`--log-cli-level=DEBUG` was causing duplicate log output.
Fixed by replacing `--log-cli-level=DEBUG` with `--log-level=DEBUG`.
`--log-cli-format` removed as is not used.

Signed-off-by: Grzegorz Chwierut <grzegorz.chwierut@nordicsemi.no>