message: use slide on remove for intervals in flow view
diff: @@ -3502,8 +3502,7 @@ export class FlowView extends ui.Component implements SearchMenu.ISearchMenuHost
  const pos1 = Math.floor(Math.random() * (len - 1));
  const intervalLen = Math.max(1, Math.floor(Math.random() * Math.min(len - pos1, 150)));
  const props = { clid: this.sharedString.client.longClientId };
  - this.bookmarks.add(pos1, pos1 + intervalLen, MergeTree.IntervalType.Simple,
  - props);
  + this.bookmarks.add(pos1, pos1 + intervalLen, MergeTree.IntervalType.SlideOnRemove, props);
  }
  this.localQueueRender(-1);
  }
  @@ -5080,7 +5079,7 @@ export class FlowView extends ui.Component implements SearchMenu.ISearchMenuHost
  this.comments.add(
  sel.start,
  sel.end,
  - MergeTree.IntervalType.Simple,
  + MergeTree.IntervalType.SlideOnRemove,
  { story: commentStory });
  this.cursor.clearSelection();
  this.localQueueRender(this.cursor.pos);
  