Prior to this commit, we would advise developers, as migration path from
Spring Boot 2.0-x metrics, to create `GlobalObservationConvention` beans
for the observations they want to customize (observation name or key
values).
`GlobalObservationConvention` are currently applied **in addition** to
the chosen convention in some cases, so this does not work well with
this migration path.
Instead, instrumentations always provide a default convention but also a
way to configure a custom convention for their observations. Spring Boot
should inject custom convention beans in the relevant
auto-configurations.
Fixes gh-33285
07766c436c