Updates for collapsed notifications

- collapsed notifs in a collapsed group - only one line and
show the conversation title
- collapsed notifs - 2 lines (separate flag) or 3 for summarization

Test: manual
Flag: android.app.nm_summarization
Flag: android.app.nm_collapsed_lines
Bug: 390217880
Change-Id: I4a2810b0ab67c97ca413b4d8326261c43a3d86b5