Refactor Lettuce connection handling in integration tests

[mp911de]

Right now, the Surefire shutdown times out due to heavy connection cleanup via the shutdown hooks. In a regular test run, we retain about 2000 open Redis connections. The cleanup requires a significant amount of time.

We should:

• Reuse pooled connections as much as possible (LettuceReactiveCommandsTestSupport causes a lot of connections)
• Revisit our method source caching to cache input parameters. right now, we create fixtures (and therefor pools) for each method via @ParameterizedRedisTest
• Release resources via method source retrieval to close resources early on
• Reuse shared ClientResources
• Use SimpleAsyncTaskExecutor as default utility in ClusterCommandExecutor