Removed unused `tests/conftest.py`
Removed unused `tests/conftest.py`

Used to contain the yaml_cfg_path() fixture; not needed anymore since
b1c5cbc ("tests/config/yaml: use pytest_collect_file() hook for YAML
files") and 816fefd ("tests/tracing: use pytest_collect_file() hook for
YAML files").

Signed-off-by: Philippe Proulx <2096628897b40c93960fdd9e24c9c883a54d4fe9@gmail.com>

efficios/barectf,efficios/barectf