feat: Enhance limit-count Plugin to support to set redis-cluster connection timeout

[hsuanlin1203]

Description

The limit-count plugin can set redis connection timeout, but can not set redis-cluster connection timeout, because utils.rediscluster only support to set read timeout (https://github.com/apache/apisix/blob/master/apisix/utils/rediscluster.lua#L27).
The default connection timeout of resty redis cluster is 1 second and I need longer.