Our build scripts pass `$(GO_TAGS)` to `-tags` go compile flags, except
for `make dev`, where `$(NOMAD_UI_TAG)` is used.  This change ensures
`make dev` is inline with the rest of makefile targets.

I use the flag primarily to enable the nomad ui using the committed
compiled assets without regenerating them, as I find using stale ui
satisfactory most of the time.