Remove the triple-click event from KoToolBase

This was added in

commit a7a75f0056abf59cbce27957ab7fb0b6e64e2cb2
Author: C. Boemann <cbo@boemann.dk>
Date:   Thu Jan 12 22:13:26 2012 +0100

to make it possible to select text with triple-click. It broke
Krita, so was worked around in

commit e2ccd93765584816da70af5747e7ef7b1ce71422
Author: Dmitry Kazakov <dimula73@gmail.com>
Date:   Thu Dec 12 17:17:37 2013 +0400

    Fix too fast mouse clicks (triple clicks) issue

    BUG:328358

And we just don't need it at all anymore now that the text tool
is deprecated.