Remove jQuery-UI

This resolves conflicts and reapplies @syncguru's original removal
commit 14e3d50 following Ace template
adjustments to avoid CSS issues [1].

Fixes #21881

[1] PR #1009

core/constant_inc.php

@@ -609,12 +609,10 @@
 define( 'FTP', 1 );                                 # DISK
 define( 'ERROR_FTP_CONNECT_ERROR', 16 );            # N/A
 
-# JQuery and JQuery UI
+# JQuery
 # hashes acquired with command 'cat file.js | openssl dgst -sha256 -binary | openssl enc -base64 -A'
 define( 'JQUERY_VERSION', '2.2.4' );
 define( 'JQUERY_HASH', 'sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44=' );
-define( 'JQUERY_UI_VERSION', '1.11.4' );
-define( 'JQUERY_UI_HASH', 'sha256-xNjb53/rY+WmG+4L6tTl9m6PpqknWZvRt0rO1SRnJzw=' );
 
 # Bootstrap & FontAwesome
 define( 'BOOTSTRAP_VERSION', '3.3.6' );

core/html_api.php

@@ -207,13 +207,6 @@ function require_css( $p_stylesheet_path ) {
 function html_css() {
 	global $g_stylesheets_included;
 	html_css_link( config_get( 'css_include_file' ) );
-
-	if ( config_get_global( 'cdn_enabled' ) == ON ) {
-		html_css_cdn_link( 'https://ajax.googleapis.com/ajax/libs/jqueryui/' . JQUERY_UI_VERSION . '/themes/smoothness/jquery-ui.min.css' );
-	} else {
-		html_css_link( 'jquery-ui-' . JQUERY_UI_VERSION . '.min.css' );
-	}
-
 	html_css_link( 'common_config.php' );
 	# Add right-to-left css if needed
 	if( lang_get( 'directionality' ) == 'rtl' ) {
@@ -309,14 +302,12 @@ function html_head_javascript() {
 	if ( config_get_global( 'cdn_enabled' ) == ON ) {
 		# JQuery
 		html_javascript_cdn_link( 'https://ajax.googleapis.com/ajax/libs/jquery/' . JQUERY_VERSION . '/jquery.min.js', JQUERY_HASH );
-		html_javascript_cdn_link( 'https://ajax.googleapis.com/ajax/libs/jqueryui/' . JQUERY_UI_VERSION . '/jquery-ui.min.js', JQUERY_UI_HASH );
 
 		# Dropzone
 		html_javascript_cdn_link( 'https://cdnjs.cloudflare.com/ajax/libs/dropzone/' . DROPZONE_VERSION . '/min/dropzone.min.js', DROPZONE_HASH );
 	} else {
 		# JQuery
 		html_javascript_link( 'jquery-' . JQUERY_VERSION . '.min.js' );
-		html_javascript_link( 'jquery-ui-' . JQUERY_UI_VERSION . '.min.js' );
 
 		# Dropzone
 		html_javascript_link( 'dropzone-' . DROPZONE_VERSION . '.min.js' );