Being able to disable prom annotations

[SmaineTF1]

What was changed

Default behavior should be to have the annotations disabled at the service level.
Note that it is already enabled at the global level by default:

server:
  metrics:
    annotations:
      enabled: true

Why?

That makes easier to configure if you use the prometheus operator for instance

[SmaineTF1]

Do you need more info?

[robholland]

This is backwards incompatible, you are changing the defaults such that new users would not get the annotations. You aren't considering the top-level setting.