Remove global CONFIG_PATH variable

[tjelvar-olsson]

With dtoolcore 3.3.1 there is no longer a need to provide the global CONFIG_PATH variable to DataSet.from_uri calls.

• Remove the global variable CONFIG_PATH from dtool-info.
• Remove all references to CONFIG_PATH in all other dtool-* packages

[tjelvar-olsson]

The 3.9.0 release of dtoolcore included the helper functions:

• dtoolcore.utils.get_config_value_from_file
• dtoolcore.utils.write_config_value_to_file

reducing the need to make use CONFIG_PATH.