Editor: Update document layout only if the mark color changes

Change-Id: Ic0408e87422edcf880381a20d685b24c785919c3
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/texteditor/textmark.cpp

@@ -387,6 +387,8 @@ Utils::optional<Theme::Color> TextMark::color() const
 
 void TextMark::setColor(const Theme::Color &color)
 {
+    if (m_color.has_value() && *m_color == color)
+        return;
     m_color = color;
     updateMarker();
 }