ChangeNotes: Remove fields that read from ChangeColumns

The point of ChangeColumns is that the contents are copied into the
relevant columns in the ChangeNotes's Change instance upon loading.
Callers should just be getting these fields from the Change instead;
there weren't any callers outside of tests doing the wrong thing anyway.

Change-Id: Ib6a592e4a5b28add9ed117dbcffb03ac7a507582

java/com/google/gerrit/server/notedb/ChangeNotes.java

@@ -670,22 +670,6 @@ public class ChangeNotes extends AbstractChangeNotes<ChangeNotes> {
     return state.readOnlyUntil();
   }
 
-  public boolean isPrivate() {
-    return state.columns().isPrivate();
-  }
-
-  public boolean isWorkInProgress() {
-    return state.columns().isWorkInProgress();
-  }
-
-  public Change.Id getRevertOf() {
-    return state.columns().revertOf();
-  }
-
-  public boolean hasReviewStarted() {
-    return state.columns().hasReviewStarted();
-  }
-
   @Override
   protected void onLoad(LoadHandle handle)
       throws NoSuchChangeException, IOException, ConfigInvalidException {