Tighter match own service when trying to find suitable window to open path in.

Summary:
Current implementation matches org.kde.dolphin-.*PID while trying to exclude itself from the list of running instances.
With this fix applied only org.kde.dolphin-PID is matched.

Test Plan: Open dolphin twice. Observe only one window.

Reviewers: feverfew, #dolphin, elvisangelaccio

Reviewed By: #dolphin, elvisangelaccio

Subscribers: elvisangelaccio, kfm-devel

Tags: #dolphin

Differential Revision: https://phabricator.kde.org/D21547