TriggerMenuMT: add custom log formatter

Add a custom `logging` formatter for all child loggers in the
TriggerMenuMT package. Due to the deep module hierarchy, logger names
often become too long and make log file reading difficult. The custom
formatter now only shows the first and last module name, e.g.:

Py:TriggerMenuMT.HLTMenuConfig.UnconventionalTracking.FullScanLRTConfiguration
becomes
Py:TriggerMenuMT:FullScanLRTConfiguration

Also remove all custom logger names and use the module `__name__`
consistently.