Revert "Create a global launch shortcut (Meta+E)"

This reverts commit 58084cf7da362d77919483cbb9a7a23333ce86c5.

Plasma considers khotkeys deprecated, so we shouldn't add new users
making the migration even harder.
Dolphin should use the X-KDE-Shortcuts desktop entry instead.

More details in David's comment: https://phabricator.kde.org/D19831#437096