[1] Alert on number of objects in buckets

[OlleLarsson]

Is your feature request related to a problem? Please describe. On some clouds there's no limit on size for a bucket but there might instead be some limit on the number of objects a bucket can hold.

Describe the solution you'd like A Prometheus alert similar to this one but for the number of objects.

Describe alternatives you've considered

Additional context The metrics for this request should already exist s3_objects (according to the metrics listed here)

Definition of done: There's an alert for the number of objects in s3 buckets.