Do not display full path in the title of the tab

Summary:
Displays the full path only in the window title, not in the tab title.

Screenshot for comparison: ( Dolphin on the right is without D28815 , Dolphin on left has both D28815 and this patch)

{F8240079}

Reviewers: #vdg, #dolphin, ngraham, meven

Reviewed By: #vdg, #dolphin, ngraham, meven

Subscribers: ngraham, elvisangelaccio, meven, kfm-devel

Tags: #dolphin

Differential Revision: https://phabricator.kde.org/D28857