Fix variable arguments on RedisCluster::rawCommand()

[wutsch0]

RedisCluster->rawCommand() method stub currently indicated that exactly 3 parameters would be required, but it actually requires 2 or more arguments

Code like

$redisCluster->rawCommand($key, 'expire', $key, $timeout, $mode);

gets highlighted with inspection warning

Method RedisCluster::rawCommand() invoked with 5 parameters, 3 required

although perfectly valid. Note that the original method name is not camelCase but all lower case as well (verified via reflection)

See the official phpredis stub for comparison.

This PR addresses WI-81080