non-jira: fix display or velocity code in peekview when no-access message of a...

non-jira: fix display or velocity code in peekview when no-access message of a node is empty and not accessible

src/main/java/org/olat/course/nodes/st/_content/peekViewWrapper.html

 <div id="$r.getCId()" class="o_entry $coursenode.getType()">
 	<div class="o_shorttitle"><h4>$r.render("nodeLink")</h4></div>
 #if(!$accessible)
+	#if ($coursenode.getNoAccessExplanation())
 	<div id="o_msg_info" class="panel panel-info o_block">
  		<div class="panel-heading">$r.translate("info.header")</div>
   		<div class="panel-body">$coursenode.getNoAccessExplanation()</div>
 	</div>
+	#end
 #else
 	#if ($coursenode.getLongTitle() &&  $coursenode.getLongTitle() != "")
 		<div class="o_displaytitle">$r.escapeHtml($coursenode.getLongTitle())</div>