dhcp: replace IP reservation with --no-ping option

It was discovered that the ping check used by default by dnsmasq DHCP
server is actually the root cause of the issue with changing IPs of DUTs
connected to Satlab. Changing the approach as it will be way easier to
provide to Satlab users.

BUG=b/321300259
TEST=manual

Change-Id: Ie8a8a43b27a99d32a59c46032e027269ffd9787c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/moblab/+/5416375
Reviewed-by: Michal Matyjek <mmatyjek@google.com>
Commit-Queue: Tomasz Jakubowski <jakubowskit@google.com>
Tested-by: Tomasz Jakubowski <jakubowskit@google.com>
4 files changed