[kcms/baloo] Fix path to database read from the environment variable
BALOO_DB_PATH holds the location of the folder where the index will live, not the full path to the index. So if that environment variable is set, we need to append the name of the index file to it to yield the full path to the index file.
This is a follow-up to !432 (merged).
cc @bruns
Edited by Nate Graham