Remove attempt to start long gone baloo_file_cleaner

Summary:
The standalone index cleaner has been replaced almost 5 years by
functionality implemented in baloo_file.

Reviewers: Baloo, ngraham

Reviewed By: Baloo, ngraham

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D27579

(cherry picked from commit 616a99165edae45dc6d90f619d2d1e3ab8192f14)