dictConfig in misc/greeter is excessive

[ei-grad]

It doesn't make sense to have the copy-pasted verbose logging configuration in main.py, main_pingpong.py and main_pingpong_servicer.py, which has the effect equal to

logging.basicConfig(format="[%(asctime)s - %(name)s - %(levelname)s]:  %(message)s", level=logging.WARNING)

[standy66]

I was kinda in a hurry when I did that, and just copy-pasted some leftover code from previous projects. Feel free to contribute.