[BUGFIX] Do not prepend siteUrl in RTE when handler keyword is present

see https://review.typo3.org/#/c/44713/

Resources/Public/JavaScript/RteLinkBrowser.js

@@ -101,8 +101,8 @@ define(['jquery', 'TYPO3/CMS/Recordlist/LinkBrowser'], function($, LinkBrowser)
 			input = 'id=' + input.substr(5);
 		}
 
-		// if it's no mail or external link, we always prepend the siteUrl
-		if (input.indexOf('mailto:') !== 0 && !attributes['data-htmlarea-external']) {
+		// if there is no handler keyword (mailto:, record:, etc) or an external link, we always prepend the siteUrl
+		if (!/^\w+:/.test(input) && !attributes['data-htmlarea-external']) {
 			input = RteLinkBrowser.siteUrl + '?' + input;
 		}