Drop the Dashboard Effect
Review Request #125686 - Created Oct. 18, 2015 and submitted
Basically dead code given that Plasma doesn't have a dedicated dashboard mode anymore and also doesn't set the required window role for it to work. By deleting we save one string comparison for each newly opened window.
Compiles without the effect. Verified that "plasma-dashboard" is nowhere set in plasma-framework, plasma-workspace and plasma-desktop.