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/text/RuleBasedCollator.java

@@ -278,6 +278,7 @@ public class RuleBasedCollator extends Collator{
      * example, build rule "a < ? < d" will cause the constructor to
      * throw the ParseException because the '?' is not quoted.
      */
+    @SuppressWarnings("this-escape")
     public RuleBasedCollator(String rules) throws ParseException {
         this(rules, Collator.CANONICAL_DECOMPOSITION);
     }