XWIKI-22138: Tips panel does not have underline style for links in subwiki (#3094)

* Replaced the standard CSS class selector with a `class contains` selector

(cherry picked from commit e3e57ef0)

xwiki-platform-core/xwiki-platform-flamingo/xwiki-platform-flamingo-skin/xwiki-platform-flamingo-skin-resources/src/main/resources/flamingo/less/general.less

@@ -161,7 +161,7 @@ body.content {
 
     // UIs where we want to underline outside of content.
     .xdocLastModification,
-    .panel.HelpTipsPanel,
+    .panel[class*="HelpTipsPanel "],
     .commentauthor {
       & a {
         text-decoration: underline;