* Kafka Streams metrics in the binder for Boot 2.2 users are streamlined to
reflect the Micrometer native support added with version 1.4.0 which is
available through Boot 2.3. While Boot 2.3 users will get this native support
from Micrometer, Boot 2.2 users will still rely on the custom implementation
in the binder. This commit aligns that custom implemenation more with
the native implementation.
* Disable the custom Kafka Streams metrics bean which is mentioned above
(KafkaStreamsBinderMetrics) when the application is on Boot 2.3, as this
implementation is only applicable for Boot 2.2.x.
* Update docs
Resolves https://github.com/spring-cloud/spring-cloud-stream-binder-kafka/issues/880