As pointed out by Fu Hanxi, the pytest_build_system job is currently
using --parallel-index and --parallel-count, which are provided by
pytest-embedded, so we should not disable it. Moreover to properly
disable pytest-embedded we should use "no:pytest_embedded". Meaning
this probably was not working as indented anyway.
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>