Remove Comparable interface from ScoreAccessor (#35519)

The way ScoreAccessor implements `compareTo()` is problematic because it doesn't
completely follow the Comparable contract, specificaly symmetry (if x is a
ScoreAccessor and y any Number then x.comparTo(y) works, but y.compareTo(x)
generally does not even compile). Fortunately we don't seem to use the fact that
ScoreAccessor is a Comparable anywhere, so we can simply remove it.

Author: Christoph Büscher

server/src/main/java/org/elasticsearch/script/ScoreAccessor.java

@@ -30,7 +30,7 @@
  * The provided {@link DocLookup} is used to retrieve the score
  * for the current document.
  */
-public final class ScoreAccessor extends Number implements Comparable<Number> {
+public final class ScoreAccessor extends Number {
 
     Scorer scorer;
 
@@ -65,9 +65,4 @@ public float floatValue() {
     public double doubleValue() {
         return score();
     }
-
-    @Override
-    public int compareTo(Number o) {
-        return Float.compare(this.score(), o.floatValue());
-    }
 }