Review fixes for jaxrs-common:testing (#18051)

Author: otelbot[bot]

instrumentation/jaxrs/jaxrs-common/testing/src/main/java/io/opentelemetry/instrumentation/jaxrs/AbstractJaxRsHttpServerTest.java

@@ -145,7 +145,7 @@ void subResourceLocator() {
                             .hasParent(trace.getSpan(3))));
   }
 
-  enum AsyncResponseTestKind {
+  private enum AsyncResponseTestKind {
     SUCCESSFUL("succeed", 200) {
       @Override
       void assertBody(String body) {
@@ -239,7 +239,7 @@ void shouldHandleAsyncResponse(AsyncResponseTestKind testKind) throws Exception
             });
   }
 
-  enum CompletionStageTestKind {
+  private enum CompletionStageTestKind {
     SUCCESSFUL("succeed", 200) {
       @Override
       void assertBody(String body) {