optimize lettuce plugin

[darcydai]

Fix

• Add a unit test to verify that the fix works.

• Explain briefly why the bug exists and how to fix it.

• Update the CHANGES log.

This is a big change for the lettuce plugin

Lettuce is an async Redis client base on netty, and wide use in our company.
Recently I found almost every lettuce span has the time elapsed less than 1ms and has a long gap between two spans. After reading the lettuce source code, I found the plugin some bug.
because lettuce is an async framework base on netty, old interceptor named 'RedisChannelWriterInterceptor' stop span in after method can not record the time elapsed, it should be close in 'RedisCommand#complete' or 'RedisCommand#completeExceptionally' or 'RedisCommand#cancel' called when Redis server response
lettuce plugin record nothing when lettuce work on reactive mode (project reactor)
record Redis peer in skywalking dynamic field can simplify

The new plugin can work with Redis standalone and Redis Sentinel and Redis cluster(old version can not). Redis cluster and Redis sentinel need to use docker-compose. I do not know how to make scenarios test in this two cluster model

[wu-sheng]

The new plugin can work with Redis standalone and Redis Sentinel and Redis cluster(old version can not). Redis cluster and Redis sentinel need to use docker-compose. I do not know how to make scenarios test in this two cluster model

It is fine to skip that. If you want, it is better to update support list doc to mention all these.

[wu-sheng]

LGTM. @darcydai Do you need to update the document to mention this?

The new plugin can work with Redis standalone and Redis Sentinel and Redis cluster(old version can not). Redis cluster and Redis sentinel need to use docker-compose. I do not know how to make scenarios test in this two cluster model

[darcydai]

LGTM. @darcydai Do you need to update the document to mention this?

The new plugin can work with Redis standalone and Redis Sentinel and Redis cluster(old version can not). Redis cluster and Redis sentinel need to use docker-compose. I do not know how to make scenarios test in this two cluster model

where should I write this？

[wu-sheng]

How about adding (cluster..) after redis on this page?

https://skywalking.apache.org/docs/skywalking-java/latest/en/setup/service-agent/java-agent/supported-list/