Introduce configuration options for ClusterCommandExecutor via Jedis

[he7g]

see

spring-data-redis/src/main/java/org/springframework/data/redis/connection/ClusterCommandExecutor.java

Line 90 in 125342f

ThreadPoolTaskExecutor threadPoolTaskExecutor = new ThreadPoolTaskExecutor();

why use coreSize 1 by default? when exec unlink keys, will use the executor, it's single thread, so so so slowly!!

[mp911de]

We should also move off the thread pool when using Lettuce as lettuce is async out of the box.

[he7g]

Good, I agree.