Bug 581856: Remove deprecated YAppearance class

Remove the YAppearance class, deprecated since v8.0.0.

Deprecated in commit 1748d6f.

[Removed] o.e.t.internal.tmf.core.presentation.YAppearance

Change-Id: I52cf6015107dca1786b632cc7e11cf6f13f80cc0
Signed-off-by: Marco Miller <marco.miller@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/c/tracecompass/org.eclipse.tracecompass/+/201514
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Trace Compass Bot <tracecompass-bot@eclipse.org>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>