[Safety Labels] Log metrics

Log metrics for:

- Views of data sharing updates page
- Clicks on individual updates in the data sharing updates page
- Views/clicks/dismissals of the data sharing updates notification

Also do the following:

- Add a TODO about refactoring
- Change cancelAndJoin to just cancel
- Dismiss notifications once they become out of date

Test: manual
Bug: 274317605
Bug: 271588305
Change-Id: Iab1b83c4156b206dfb6af1be6768322aa2937251