small fix to extract sub URL from Jar URL

Author: ldematte

libs/entitlement/src/main/java/org/elasticsearch/entitlement/runtime/api/ElasticsearchEntitlementChecker.java

@@ -656,7 +656,7 @@ private URL extractJarFileUrl(URL jarUrl) {
         }
 
         try {
-            return new URL(spec.substring(0, separator + 1));
+            return new URL(spec.substring(0, separator));
         } catch (MalformedURLException e) {
             return null;
         }