Fix python log config file

[jiangpengcheng]

Make the python log config template more robust

It was using formatter_formatter for text format and formatter_json for json format, but when Rolling is enabled, it will use the formatter_formatter to get the formatter, regardless of the log format, and then cause an error:

Traceback (most recent call last):
  File "/pulsar/instances/python-instance/python_instance_main.py", line 318, in <module>
    main()
  File "/pulsar/instances/python-instance/python_instance_main.py", line 244, in main
    log.init_logger(logging_level, log_file, args.logging_config_file)
  File "/pulsar/instances/python-instance/log.py", line 91, in init_logger
    logging.config.fileConfig(logging_config_file)
  File "/usr/local/lib/python3.12/logging/config.py", line 91, in fileConfig
    handlers = _install_handlers(cp, formatters)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/logging/config.py", line 170, in _install_handlers
    h.setFormatter(formatters[fmt])
                   ~~~~~~~~~~^^^^^
KeyError: 'formatter'

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