SpringBoot "micrometer.observations.*" configuration properties should be "management.observations.*"

Introducing the micrometer.observations.annotations.enabled configuration property in that namespace was a mistake introduced in #39128 and we should move it to management.observations.annotations.enabled.

As part of this issue, we should try to support both and deprecate micrometer.observations.annotations.enabled in our metadata, for removal in a future Spring Boot version.