[effects/minimizeanimation] Delete useless comments
Summary:
Comments like "// Call the next effect." are sort of
// Add 1 to foo. foo += 1
they don't give any useful information and it would be better without
them.
Test Plan: Still compiles.
Reviewers: KWin
Subscribers: davidedmundson, kwin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D14728