Fix getResource() for the project helper, there's no / at the beginning.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@272728 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/ProjectHelper.java

@@ -99,7 +99,7 @@ public class ProjectHelper {
      * implementations.
      */
     public static final String SERVICE_ID =
-        "/META-INF/services/org.apache.tools.ant.ProjectHelper";
+        "META-INF/services/org.apache.tools.ant.ProjectHelper";
 
     /**
      * Configures the project with the contents of the specified XML file.