Fix issue 489 - trace level messages get evaluated to send to Pulumi engine

[lbialy]

Fansi has some issues with some ansi escape codes as reported in #489. This does not fix the inner issue, we just stop sending trace log events to the engine and that prevents evaluation of the lines that cause the problem. Alternative would be to stop using pprint/fansi combo for debug but that would make debugging experience much worse so no go.

Therefore this is fixed for the end user, weird fansi (?) bug persists on trace level and can / will come back to bite us in debugging.