Avoid using PHPStan --debug when generating reports

Testing with GTD MR8
As-is with --debug in all phpstan commands, we get invalid .xml and the red errors in the report tab
https://git.drupalcode.org/project/gitlab_templates_downstream/-/merge_r...
https://git.drupalcode.org/project/gitlab_templates_downstream/-/pipelin...

Now using this MR375
https://git.drupalcode.org/project/gitlab_templates_downstream/-/pipelin...
The MR report tab is green with no .xml errors, even though we still get the debug output in the viewable log.

Ready for review

Added screenshots to show the problem, because these are not viewable when the last run is clean.

Thanks for the issue and MR. I looks good. RTBC.

Small thing, but worth fixing. When using --debug you don't expect the output files to be corrupt. Especially as that is probably precisely the time when you need to examine the files.

I have also just checked that this works when there is no '--debug' in the original string, and it does work OK