Remove orphan CSS selectors in phui/phui-form-view.css
Summary:
* `drag-and-drop-file-target`
** Added in https://we.phorge.it/rP8573a1e14231867a145f09535e3e297c4dcda3e2; usage removed in https://we.phorge.it/rPdd76143399d8b77a14baca44f99051aa6298e487 by deleting `webroot/rsrc/js/core/behavior-drag-and-drop.js`
* `drag-and-drop-instructions`
** Added in https://we.phorge.it/rP109a202b6c77d61141d8ff4c98ce2548064334ef; usage removed in https://we.phorge.it/rPdd76143399d8b77a14baca44f99051aa6298e487 by deleting `webroot/rsrc/js/core/behavior-drag-and-drop.js`
* `recaptcha_only_if_privacy`
** Added in https://we.phorge.it/rP1329b7b51ef88825b36cf47b3c680542c2895579, looks like it has never been used
Test Plan: Grep the code for each CSS selector (`grep --exclude="*.css" -R 'some-search-string' .`), also do partial searches, get no results.
Reviewers: O1 Blessed Committers, valerio.bozzolan
Reviewed By: O1 Blessed Committers, valerio.bozzolan
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D26011