Probably wrong time unit for shutdown timeouts in docs

[pboguslawski]

According to #1300 shutdown timeouts specified in cli params should be in minute units. Practical tests in debian 11 (ganeti 3.0.2-1~deb11u1) using gnt-instance shutdown --timeout show that it might be not true and --timeout values are in seconds not minutes:

# time gnt-instance shutdown --timeout=5 myguest
Waiting for job 165117 for myguest.mydomain ...

real    0m12.740s
user    0m0.256s
sys     0m0.029s

# time gnt-instance shutdown --timeout=20 myguest
Waiting for job 165127 for myguest.mydomain ...

real    0m27.798s
user    0m0.255s
sys     0m0.032s

# time gnt-instance shutdown myguest
Waiting for job 165122 for myguest.mydomain ...

real    2m8.371s
user    0m0.239s
sys     0m0.044s

# time gnt-instance shutdown --timeout=180 myguest
Waiting for job 165131 for myguest.mydomain ...

real    3m8.618s
user    0m0.254s
sys     0m0.040s

Please verify (other shutdown params also i.e. in gnt-instance export) and fix docs if required.

[pboguslawski]

Just checked in debian 11 (ganeti 3.0.2-1~deb11u1) that

gnt-backup export -n mynode.mydomain --shutdown-timeout=600 --submit --print-jobid myguest

waits 10 minutes (600 seconds) for VM (that ignores shutdown signal from ganeti) to be killed before backup so docs should be fixed for export also (and probably other stuff changed in #1429 also).