_rewrite_tarball in paused should remove the tmpdir after use

[rjbs]

[rspier]

This is probably because we're using the function based API instead of the object based API:

https://perldoc.perl.org/File::Temp#tempdir says:

This is the recommended interface for creation of temporary directories. By default the directory will not be removed on exit (that is, it won't be temporary; this behaviour can not be changed because of issues with backwards compatibility). To enable removal either use the CLEANUP option which will trigger removal on program exit, or consider using the "newdir" method in the object interface which will allow the directory to be cleaned up when the object goes out of scope.

The current paused process has been running since May 13th.

I just restarted it, and the temp dirs were all cleaned up.

Maybe we should switch to the object interface so we can better control the lifecycle? See #570