Probe SSH in openwrt healthcheck

[olekoliinyk]

Problem

test_openwrt_simulate_network_down failed in openwrt-gw-03: the test could not open an SSH session to the router and timed out after 30s.
The container was reported as healthy, because the healthcheck only opened a TCP connection to port 22.

Solution

• Make the healthcheck ask for the SSH greeting instead of just opening a socket (drop it as SSH is more complete check in this case)
• Raise openwrt healthcheck timeouts to 30s, since the check can now wait up to 20s
• Drop the QEMU guest agent block: no guest agent socket is ever created, and it queried the QMP socket instead, so it could never have worked

☑️ Definition of Done checklist

• Commit history is clean (requirements)
• README.md is updated
• Functionality is covered by unit or integration tests

[asledzinskiy]

+1

[matislovas]

+1