[Cocoa] Slack.com audible notifications interrupt Music.app and steal NowPlaying status
<rdar://problem/114667001>
Pull request: https://github.com/WebKit/WebKit/pull/19610
Committed 269948@main (c320bb08e139): <https://commits.webkit.org/269948@main> Reviewed commits have been landed. Closing PR #19610 and removing active labels.