Backport #26233 by @silverwind
Resizing the comment editor can be a very expensive operation because it
triggers page reflows, which on large PRs can take upwards of seconds to
complete. Disable this mechanism on the diff page only where we know
that the page can get large.
Fixes https://github.com/go-gitea/gitea/issues/26201 for the textarea
editor.
I don't think this can be fixed for EasyMDE because as far as I can
tell, it exposes no option to disable this resizing.
Co-authored-by: silverwind <me@silverwind.io>
0f265a2489