Automatic merge from submit-queue

Adds termination hook in reboot test for debugging

From #33405 and #36230.

Logs the SSH command issued for dropping inbound / outbound traffic to file and dump it out when test ends.

The first `sudo iptables -t filter -nL` is called to confirm the rules are injected. The second `sudo iptables -t filter -nL` is to check whether the rules get clobbered. Adds `date` in between to check time frame.

@bprashanth @freehan