Added guard for restClient shutdown freeze.

[AlexeyKuznetsov-DD]

What Does This Do

Adds a maximum 10-second timeout for the Redis client shutdown.
Previously, this test had a high chance of freezing on CI.
After multiple retries, I collected a thread dump from a hung test:

"Test worker" #1 [10060] prio=5 os_prio=0 cpu=7203.66ms elapsed=421.50s tid=0x00007fecf0031970 nid=10060 in Object.wait()  [0x00007fecf764c000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait0([email protected]/Native Method)
	- waiting on <no object reference available>
	at java.lang.Object.wait([email protected]/Object.java:366)
	at java.lang.Object.wait([email protected]/Object.java:339)
	at io.netty.util.concurrent.DefaultPromise.await(DefaultPromise.java:254)
	- locked <0x00000000d816e6f8> (a io.netty.util.concurrent.DefaultPromise)
	at io.netty.util.concurrent.DefaultPromise.await(DefaultPromise.java:32)
	at io.netty.util.concurrent.AbstractFuture.get(AbstractFuture.java:31)
	at com.lambdaworks.redis.AbstractRedisClient.shutdown(AbstractRedisClient.java:277)
	at com.lambdaworks.redis.AbstractRedisClient.shutdown(AbstractRedisClient.java:225)
	at com.lambdaworks.redis.AbstractRedisClient$shutdown.call(Unknown Source)
	at Lettuce4ClientTestBase.cleanup(Lettuce4ClientTestBase.groovy:83)

The freeze was traced to line 83:

redisClient.shutdown()

To prevent indefinite blocking, I refactored it to enforce shutdown with a timeout:

    try {
      redisClient.shutdown(5, 10, TimeUnit.SECONDS)
    } catch (Throwable ignored) {
      // No-op.
    }

Motivation

Improve CI stability by preventing test freezes.

[ygree]

Looks good!