icons/actions: drop wrongly mirrored rtl variants of media icons

These shouldn't be mirrored, because media icons are depicting icons found on physical devices. These physical devices do not have mirrored icons in RtL cultures.

These were initially introduced because of a wrong assumption that GNOME had these icons, despite the fact that it did not and does not have these icons. Likewise, since this is drawing from skeumorphism from real-world devices that are largely the same across cultures, these icons are not mirrored by any other UI that I am aware of, not by English-language software localised into RtL cultures, or software produced by people in RtL cultures.