Improve Multi-IP Device Discovery Logic and Subnet Scan Coverage

During device discovery, when a device presents multiple IP addresses and SNMP succeeds on one of them, the discovery process currently adds the device using that IP without further attempting other IP addresses that might yield a successful SSH connection. This can result in devices being onboarded as SNMP-only even when a more complete SSH-based connection was achievable through a different IP on the same device. This enhancement proposes that discovery continue evaluating all known IP addresses for a device until the most complete access method (SSH preferred over SNMP-only) is confirmed, rather than stopping at the first successful protocol match. Additionally, subnet range scans should guarantee that every IP address in the defined range is attempted, including at minimum a ping, so that no address is silently skipped. This would improve discovery completeness and access-method accuracy, reducing the need for manual review and re-scanning of missed or improperly onboarded devices.