Fix print time metrics not being cleared correctly

[hyperair]

This fixes an issue where print time metrics for a path that has completed don't get fully cleared after print completion

[arcnmx]

Trying this seemed to result in an error after a cancel?

Exception in thread Thread-102: TypeError: PrometheusExporterPlugin.print_deregister_callback() takes 2 positional arguments but 51 were given Exception in thread Thread-106: TypeError: PrometheusExporterPlugin.print_deregister_callback() missing 1 required positional argument: 'label'

[hyperair]

Oops, just fixed that