RedisCacheConnectionPoolManager raises connections without limits

[Aequitash]

I use StackExchange.Redis.Extensions.Core of version 6.3.4

On each failed request RedisCacheConnectionPoolManager will create new connections. For example it happens when redis database is disabled or invoked restart

Steps to reproduce:

1. Run API endpoint which on every request will make any request to redis. RedisConfig.PoolSize is 2
2. Enable Runner in postman which will hit this endpoint 10000 times without delay
3. Run in redis CLI command "client list" -> there will be 2-5 connections
4. Invoke redis reboot without disabling Runner
5. When reboot will be finished run redis CLI command "client list" -> where will be ~20 connection. Which will be much more then expected when poolSize is 2

Expected: Same 2-5 connections

Reason:
In StateAwareConnection.ConnectionFailed method raised invalidateConnectionCallback which referenced to EmitConnection method of RedisCacheConnectionPoolManager. This method creates new connection on each failed request. But old connections will not be closed.

Possible workaround:

1. Call Invalidate() method in ConnectionFailed
2. Update Invalidate() method to use multiplexer?.Close() instead of multiplexer?.Dispose()

[Aequitash]

Added PR: #321

[Aequitash]

Fixed in version 6.3.5