[deployment] Ensure netem are properly applied

[the-glu]

When performing various load tests, I noticed that sometime, interface order is not the same. Also, a container attached to a network later if it fail would not apply netem commands (who is probably the reason for interface swapped).

This PR:

• Restart container instead of reattaching them to a network
• Make startup script detect the correct interface instead of guessing
• Make startup script stop if they didn't detect the correct interface: we don't want to silently don't apply netem config.

[barroco]

See comments