Disable attachment element setting when lock down mode is enabled.
<rdar://97099213>
Pull request: https://github.com/WebKit/WebKit/pull/2493
Committed 252581@main (3bc6c5a30293): <https://commits.webkit.org/252581@main> Reviewed commits have been landed. Closing PR #2493 and removing active labels.
Reverted by https://github.com/WebKit/WebKit/pull/2820