According to the spec, specifying a custom URI when retrieving a
`javax.cache.CacheManager` might be used as a way to transmit the
location of a custom configuration file to initialize the underlying
cache manager.

If `spring.cache.config` is set, we use that information to retrieve a
CacheManager with that configuration file. Unfortunately, hazelcast does
not support this feature so we are setting the property key it expects
instead.

See https://github.com/hazelcast/hazelcast/issues/4943

Closes gh-2743