Logging configuration is not consistent and depend on setup file

[anton7811]

There are a number of small issues that makes logging functionality quite confusing in SAI-Challenger.

1. SAI-C syncd logging option --loglevel may confuse the user with the native pytest option --log-level. I suggest renaming syncd related option.
2. --log-level option behavior depends on the selected setup JSON. Example: If there is a PTF dataplane - --log-level is ignored (probably because common/sai_dataplane/ptf/sai_ptf_dataplane.py has a custom logging setup). But if there is a snappi and no PTF - --log-level functions as expected and the user can select desired CLI logging level.
3. There is no good example in the test cases of how to use logging.