e2e test support: Store test pod logs and events

[sutaakar]

Name of Feature or Improvement

Pod logs and events for test namespaces should be stored to help identifying test issues.

Description of Problem the Feature Should Solve

Right now the test failures can be hard to investigate as the logs of pods in test namespaces aren't stored anywhere. Also events in the namespace should be stored, to identify issues like image pull problems.

Describe the Solution You Would Like to See

e2e tests will store pod logs and namespace events in the output directory (where the Ray job logs are stored for now).

Describe Alternatives You Have Considered

N/A

Additional Context