Do not display a buggy filesize for non local files
Summary:
When displaying a virtual folder or remote drive the folder size in the information panel is wrong.
The subDirectoriesCount function supports only local files.
It creates a bug where when a url such as recentdocuments:/ is displayed in dolphin, the count reflected in the size field is in fact the count of its path meaning the number of files in the root folder /.
Test Plan: Manual
Reviewers: Dolphin, ngraham, elvisangelaccio
Reviewed By: Dolphin, elvisangelaccio
Subscribers: Baloo
Tags: Baloo
Differential Revision: https://phabricator.kde.org/D22529