TestDistributedStatsComponentCardinality: Remove @BadApple anotation

This test was originally anotated @BadApple ~2018-10-14 as pat of SOLR-12028.

So far in 2019, it has failed in 62 jenkins-BadApple builds, but all prior to 2019-06-14.

Since we no longer have logs from those older jenkins builds, it's hard to be certain how/why
this test was failing, or why exactly it *stopped* failing -- but a likely suspect is that
the root cause of the problem may have been fixed as part of the Jetty upgrade in SOLR-13541.

solr/core/src/test/org/apache/solr/handler/component/TestDistributedStatsComponentCardinality.java

@@ -104,7 +104,6 @@ public class TestDistributedStatsComponentCardinality extends BaseDistributedSea
     
   }
 
-  @BadApple(bugUrl="https://issues.apache.org/jira/browse/SOLR-12028") // 14-Oct-2018
   public void test() throws Exception {
     buildIndex();