🐞 Bug `.nkit.iso` => `.rvz` conversion does not delete `.iso~` files

Issue Description

.nkit.iso => .rvz conversion does not delete temporary .iso~ files.

E.g. When running:

nkit \
    -task convert \
    -in "<slow-big-hdd>" \
    -tmp "<fast-small-nvme>" \
    -fixFiles "<...>" \
    -dat "<...>" \
    -r n \
    -v y;

To convert .nkit.iso's into .rvz's, which is way faster due to processing on the NVMe and afterwards storing on the HDD.

However after a file has been fully processed, an .iso~ file remains in the -tmp directory.

Which leads to the small NVMe getting full rather quickly, which could abruptly halt my system, since it's also the drive on which the OS runs.

I just did some tests regarding this issue, my findings are:

The -tmp parameter is unrelated to the issue, since it also occurs if -out and -tmp are the same.
It's related to two step conversion, since -task expand does not have the issue
It still occurs if NKit finishes it's task (.iso~ files are not cleaned up after all conversions finish)

I attached a log file with the used NKit commands + tree results before/after NKit-Tests-One-Two-Step-Conversion-Same-Temp-Directory.md

It's been reproduced by @cgar and confirmed by @Nanook + @johnsanc there.