Managed Media Source on iPhone should only be available if airplay source alternative is present or if AirPlay is explicitly disabled
<rdar://problem/109130836>
Pull request: https://github.com/WebKit/WebKit/pull/13694
Committed 264270@main (0a9b7c59e3fa): <https://commits.webkit.org/264270@main> Reviewed commits have been landed. Closing PR #13694 and removing active labels.