Move tmp file removal parameters from cron to systemd (fate 314974)

The tmpfile cleanup parameters from /etc/sysconfig/cron need to be transformed to settings for systemd-tmpfiles in /etc/tmpfiles.d/tmp.conf. I've added a script in aaa_base.pre therefore.
Unfortunately, systemd-tmpfiles currently doesn't support owner based keep options.
Therefore I've copied OWNER_TO_KEEP_IN_TMP and TMPDIR_TO_SEARCH_OWNER into tmp.conf and execute a script that creates exclude (x) entries before each scheduled systemd-tmpfiles --clean run.