Restrict representative device selection to fully accessible devices in test replication

NetBrain currently selects representative devices for test replication without regard to whether those devices are fully accessible, which can include devices with only partial connectivity such as SNMP-only or ping-only access. This limits confidence in replication outcomes, since a failure or inconsistency may stem from incomplete device access rather than the model or intent being tested. This enhancement would allow the representative device selection process for test replication to consider only devices that are fully accessible to NetBrain, such as those with confirmed CLI or API access. Customers would gain greater confidence that replication results reflect the actual behavior of the network intent rather than being skewed by device access limitations, reducing troubleshooting effort and improving the reliability of automation testing.