Add 'paused' label to 'prefect_info_deployments' metric

[mitchnielsen]

Summary

• Adds the 'paused' label to the 'prefect_info_deployments' metric
• Also uses this value for the 'is_schedule_active' label, which is deprecated and always returns Null.
• Updates the docker-compose testing setup to use Prefect 3

Related to PLA-224

Testing

I ran docker-compose up -d and created a deployment with a schedule:

from prefect import flow

@flow
def my_flow():
    print("Hello, Prefect!")

if __name__ == "__main__":
    my_flow.serve(name="my-first-deployment-scheduled", cron="* * * * *")

Then I checked the prometheus metrics to confirm that is_schedule_active now has a value, and that it matches the opposite of the paused value:

Next I paused the deployment from the UI and confirmed paused=True and is_schedule_active=False:

[mitchnielsen]

@ubiquitousbyte FYI in case you want/have time to take a look before we merge to see if this addresses what you were seeing.

[ubiquitousbyte]

@mitchnielsen great work here. Thanks!