fix(kuma-cp): delete an empty TimeoutConfigurer

[lobkovilya]

Summary

ProvidedEndpointCluster and PassThroughCluster created clusters with an empty TimeoutConfigurer that was overriding values from the Timeout policy.

Full changelog

• delete TimeoutConfigurer from ProvidedEndpointCluster
• delete TimeoutConfigurer from PassThroughCluster
• add Configure(envoy_clusters.DefaultTimeout()). where we don't have Timeout policy.
• add unit tests

Issues resolved

Fix #4475

Documentation

• Link to the website documentation PR

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Update UPGRADE.md with any steps users will need to take when upgrading.
• Add backport-to-stable label if the code follows our backporting policy

[michaelbeaumont]

Is there a way to not have to "remember" to add .Configure(DefaultTimeout) for every cluster?

[lobkovilya]

Is there a way to not have to "remember" to add .Configure(DefaultTimeout) for every cluster?

@michaelbeaumont I was thinking about that. I see a few options:

1. we can panic if you're trying to create a cluster without timeouts
2. we can add Timeout as a parameter to every cluster's constructor like ProvidedEndpointCluster(name string, hasIPv6 bool, timeout mesh_proto.Timeout, endpoints ...core_xds.Endpoint). But then it's still easy to forget about timeouts when you create a new type of cluster
3. we can leave it as it is; the worst-case – configuration will be rejected by Envoy because connectTimeout is mandatory

[michaelbeaumont]

3. we can leave it as it is; the worst-case – configuration will be rejected by Envoy because connectTimeout is mandatory

ah ok that I wasn't aware of, yeah maybe that's enough then.