[TESTS] fix circuit breaker tests for remote clusters and bwc

Adds additional version checks in NodeStats for older versions

When using an external cluster (backwards compatibility tests), the act
of checking the request breaker requires a network buffer, which
increments the breaker. This change only checks the request breaker in
InternalTestCluster and uses Guice to retrieve it instead of
a (possible) network request.

Also removed the now unused InternalCircuitBreakerService class