use method reference and avoid parallel stream

From @mina-asham,

I would avoid `parallelStream` here:
1. I don't really think it's that intensive of an operation that you are going to get a gain
2. It's going to use the shared forkjoin pool and might affect other operations

Also we can use the method reference for the map operation.

Co-authored-by: Mina Asham <mina.asham@hotmail.com>

Author: sazzad16

src/main/java/redis/clients/jedis/JedisSentinelPool.java

@@ -170,7 +170,7 @@ public JedisSentinelPool(String masterName, Set<HostAndPort> sentinels,
   }
 
   private static Set<HostAndPort> parseHostAndPorts(Set<String> strings) {
-    return strings.parallelStream().map(str -> HostAndPort.parseString(str)).collect(Collectors.toSet());
+    return strings.stream().map(HostAndPort::parseString).collect(Collectors.toSet());
   }
 
   @Override