Change constructor visibility in SpeedOrPace class

Adjusted the visibility of the constructor in the `SpeedOrPace` abstract inner static class from public to protected. This aligns with best practices for abstract classes and clarifies its intended use.

Ref: Issue regarding the visibility of the constructor in `SpeedOrPace`

src/main/java/de/dennisguse/opentracks/viewmodels/GenericStatisticsViewHolder.java

@@ -69,7 +69,11 @@ public abstract static class SpeedOrPace extends GenericStatisticsViewHolder {
 
         private final boolean reportSpeed;
 
-        public SpeedOrPace(boolean reportSpeed) {
+        //Change this constructor's visibility to protected
+//        public SpeedOrPace(boolean reportSpeed) {
+//            this.reportSpeed = reportSpeed;
+//        }
+        protected SpeedOrPace(boolean reportSpeed) {
             this.reportSpeed = reportSpeed;
         }