`preview-hidden-comments` broken on new issue UI

[fregante]

Context: #7856

Test URL

refined-github/sandbox#47

[SunsetTechuila]

note on preview-hidden-comments: comment body ('[class^="IssueCommentViewer-module__IssueCommentBody"]') is removed from the DOM when the comment is hidden, so we have to either get the data from the react props or by using api

#7856 (comment)

[fregante]

This was actually the case before too. Sometimes GitHub would load the old comment, sometimes it wouldn't. If the reason is never available without an HTTP request we should drop the feature.

Do the global react props include it at least some of the time?