8325189: Enable this-escape javac warning in java.base

Reviewed-by: alanb, erikj, naoto, smarks, ihse, joehw, lancea, weijun

src/java.base/share/classes/java/util/concurrent/StructuredTaskScope.java

@@ -413,6 +413,7 @@ public class StructuredTaskScope<T> implements AutoCloseable {
      * @param name the name of the task scope, can be null
      * @param factory the thread factory
      */
+    @SuppressWarnings("this-escape")
     public StructuredTaskScope(String name, ThreadFactory factory) {
         this.factory = Objects.requireNonNull(factory, "'factory' is null");
         if (name == null)