[CAD-1926] Retired pools should be ignored.

[ksaric]

https://jira.iohk.io/browse/CAD-1926

Tested on qa-shelley.
Testing instructions. You first need to enable TESTING_MODE. When you do that you can check the existing metadata:

curl --verbose --header "Content-Type: application/json" http://localhost:3100/api/v1/metadata/fc80a2a814338475c737df5d1c50253046c8c04eb3663336af7beb38/93cf2f2fead6c419ccaae1a41f0786de4b9daefea7074d7bda3d288e76e20a97

Check the retired pools:

curl --verbose --header "Content-Type: application/json" http://localhost:3100/api/v1/retired

Then add a retired pool (simulate what the chain will do, this is why we need TESTING_MODE):

curl --verbose --header "Content-Type: application/json" --request PATCH --data '{"poolId":"fc80a2a814338475c737df5d1c50253046c8c04eb3663336af7beb38"}' http://localhost:3100/api/v1/retired

Now notice it's available in the list:

curl --verbose --header "Content-Type: application/json" http://localhost:3100/api/v1/retired

And you can no longer fetch the metadata:

curl --verbose --header "Content-Type: application/json" http://localhost:3100/api/v1/metadata/fc80a2a814338475c737df5d1c50253046c8c04eb3663336af7beb38/93cf2f2fead6c419ccaae1a41f0786de4b9daefea7074d7bda3d288e76e20a97

[ksaric]

This PR addresses:

• retired pools are ignored #76
• Do not serve data for retired pools #35
• improve byron logs #74

Once this is merged, they can be closed.