Remove shortcut for detach tab

Currently the shortcut is Ctrl+Shift+L which is close too
Ctrl+Shift+K. Ideally we want detach tab to not be a shortcut that can
be accidently pressed.

See https://invent.kde.org/kde/konsole/-/issues/6

(cherry picked from commit a889f6aa4b2bee17b01721234c6b2f4b1dd271f6)