cable-guy: only skipping adding dhcp server if the ip is on the inter… #1796

Job	Run time
python-tests	2m 48s
frontend-tests	1m 52s
deploy-docker-images (bootstrap, blueos, linux/arm/v7,linux/arm64/v8,linux/amd64)	3m 0s
deploy-docker-images (core, blueos, linux/arm/v7,linux/arm64/v8,linux/amd64)	17m 42s
deploy-raspberry-image	0s
	25m 22s

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