Fixes: #9335
Spring Boot provides a `CompositeMeterRegistry` bean marked with a `@Primary`.
So, this one has to be autowired whenever we would like to deal with application
environment.
The `MicrometerNodeEnhancer` has a flaw to skip `MeterRegistry` injection if we have more than one `MeterRegistry` bean.
* Fix `MicrometerNodeEnhancer` logic to use `ObjectProvider.getIfUnique()` API
which is able to deal with the `primary` properly.
Otherwise, `null` as it was before
**Auto-cherry-pick to `6.3.x` & `6.2.x`**
e0472d887a