Automatic merge from submit-queue (batch tested with PRs 43500, 44073)

[Federation] Add option to retrieve e2e cluster config from secrets

Previously the federation e2e setup was reading member cluster configuration from the test run's kubeconfig. This change removes that dependency in favor of reading member cluster configuration from secrets in the hosting cluster, and caches the configuration to avoid having to read it separately for each test.

cc: @kubernetes/sig-federation-pr-reviews @perotinus