cve-update-db-native: clean DB if temporary file exist

cve-update-db-native: clean DB if temporary file exist

when do_populate_cve_db forced stop at certain point, the
DB execution are stoped however the temporary database
file (DB-JOURNAL) are not removed. This db-journal file
indicates that DB is incomplete and set DB in readonly
mode. So when db-journal exist, remove both DB and the
db-journal and build the DB again from scratch.

[YOCTO #13682]

Signed-off-by: Lee Chee Yang <chee.yang.lee@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>