Retry link check up to 10 times.

Updates the dhcp-all-interfaces element so that the link
check tries up to 10 times.

On some of my machines 3 times (seconds) doesn't appear to
be quite long enough...

Change-Id: Ibf7015162fc890d4de8a417b868b0301146944c0
Merge "Retry link check up to 10 times."