tmp and log files are never cleared or archived

When Load Data Infile is run, it launches a cpimport session on each PM. This leaves log files in /usr/local/mariadb/columnstore/data/bulk/log. The system never cleans or archives these files. We need these for debugging, so they need to be around for a week or so. For users that run LDI periodically by script, these files can eventually cause excessive clutter and may overfill the disk. There are also brm files left in /tmp/columnstore_tmp_files and job ,dot files cluttering /tmp. Some of these may be left by standalone cpimport also.

This is related to 12578