Add test to test plan that fills up disk space and verifies that server is running

[klizhentas]

Fill up disk space in /var/lib/teleport:

$ nohup yes

Make sure that teleport node session has not disconnected.

Note this is only possible after #4696 is forward ported to 5.0 this week.

[klizhentas]

After disk fills up and some time passes, Teleport is stopped with error:

● teleport-node.service - Teleport SSH Node Service
   Loaded: loaded (/etc/systemd/system/teleport-node.service; enabled; vendor preset: disabled)
   Active: activating (auto-restart) (Result: exit-code) since Thu 2020-11-12 16:32:15 UTC; 2s ago
  Process: 14224 ExecStart=/usr/bin/teleport start -d --config=/etc/teleport.yaml --diag-addr=127.0.0.1:3434 --pid-file=/run/teleport/teleport.pid (code=killed, signal=PIPE)
  Process: 21287 ExecStartPre=/usr/bin/teleport-ssm-get-token (code=exited, status=120)
 Main PID: 14224 (code=killed, signal=PIPE)

[zmb3]

@gabrielcorado now that you've added strict session recording modes is there something in the test plan that covers this?