Display more readable tooltip text

Summary:
Special case added for handling tooltip text when in summary page

Gets rid of the confusing "Files: 2 (100%)" and "Click to go up to parent directory"
Fixes the partition name and "Used"/"New" being concatenated without spacing in between

Reviewers: sandsmark, sitter

Reviewed By: sandsmark, sitter

Subscribers: kde-utils-devel

Differential Revision: https://phabricator.kde.org/D13876