[TRACKING ISSUE] Continue trying if initial membership event retrieval fails and client is failover [API-2171]

[hz-devops-test]

The tracking issue for the Java side PR.

See hazelcast/hazelcast#26009 for details.

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As reported in https://hazelcast.atlassian.net/browse/API-2171, the client was not continuing trying next clusters if the connected cluster fails to send initial membership event in time. I added a check about client being failover in the conn. manager and conditionally handle the case.

This PR also adds required internal getters/APIs used in the test FailoverClusterMembershipEventTest in the EE PR https://github.com/hazelcast/hazelcast-enterprise/pull/6874