activity filter "history only" hides comments in discussions

Summary

When using new 11.5 activity filter feature (https://gitlab.com/gitlab-org/gitlab-ce/issues/51323), it hides comments from resolved discussions, leaving discussions empty in "history only" mode.

Steps to reproduce

1. Go to MR with resolved discussions
2. select "history only" in activity filter
3. Toggle any resolved discussions, it opens discussion, but there are no comments

Expected behavior

All discussion widgets (resolved and unresolved) should be hidden in "Show history only".