Consumer groups scale testing

[mmaslankaprv]

We need to add tests that will cover consumer groups feature handling at scale. We need to include testing with:

• static members
• dynamic members
• adding members to existing group
• deleting topic that members are subscribed to while group is active

We may leverage client swarm tool to spawn multiple consumers. Ideally the test should be parameterized and be run with failures injector running.

JIRA Link: CORE-918

[mmaslankaprv]

Added: https://github.com/redpanda-data/client-swarm/pull/1 to enable consumer testing with client swarm tool.