Allow RedisConnectionFactories to be initialized as part of the context lifecycle

[christophstrobl]

In the current arrangement the RedisConnectionFactory implementations are implementing both, InitializingBean and SmartLifecycle (See also #2502). Though, for historic reasons they eagerly try to connect to the Redis server already in afterPropertiesSet() which is not in line with the actual intent of the method aiming to verify properties leaving the startup to Lifecycle#start().

For Checkpoint restore and CDS training runs we'd need to move this arrangement into its desired state without breaking existing applications potentially relying on the eager initialization of the connection factory.