GEODE-5700: Removed stopping cache server explicitly (apache#2433)

  * ServerStarterRule unnecessarily shutdown the cache server
  * Cache.close should automatically shut down the cache server for us

geode-dunit/src/main/java/org/apache/geode/test/junit/rules/ServerStarterRule.java

@@ -89,16 +89,6 @@ public void before() {
 
   @Override
   public void stopMember() {
-    // stop CacheServer and then close cache -- cache.close() will stop any running CacheServers
-    if (server != null) {
-      try {
-        server.stop();
-      } catch (Exception e) {
-      } finally {
-        server = null;
-      }
-    }
-
     // make sure this cache is the one currently open. A server cache can be recreated due to
     // importing a new set of cluster configuration.
     cache = GemFireCacheImpl.getInstance();
@@ -110,6 +100,7 @@ public void stopMember() {
         cache = null;
       }
     }
+    server = null;
   }
 
   public ServerStarterRule withPDXPersistent() {