Also replace alternate favicons (#141)

* Fix favicon support in Chrome with Jenkins 2.367 and later

Since jenkinsci/jenkins#6768, there is an
"alternate icon" element that needs to be removed as well.

* Simplify

---------

Co-authored-by: Tobias Gruetzmacher <tobias-git@23.gs>

src/main/webapp/simple-theme.js

@@ -7,7 +7,7 @@
 
         for (i = 0; i < links.length; i++) {
             link = links[i];
-            if (link.rel === 'shortcut icon' || link.rel === 'icon') {
+            if (link.rel.split(/\s+/).some(e => e === 'icon')) {
                 link.parentNode.removeChild(link);
             }
         }