Fix stylesheet linking in 8 icons

Summary:
These 8 icons were (partially) not recolored by the stylesheet, because their elements were either not linked to the stylesheet, or had contradicting style information.
This adds the missing class attributes and removes the wrong color definitions in the style attributes.

Furthermore, I would like to know why icons/actions/symbolic/list-remove-symbolic.svg has an additional stylesheet “current-color-scheme-6”. Is that information available?

Reviewers: ndavis

Reviewed By: ndavis

Subscribers: ndavis, kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D28362