cmd/coordinator: delete some code
cmd/coordinator: delete some code

410 Gone.

Updates golang/go#31770

Change-Id: I63c4d457918e118c6543dcfc9314c979881be15f
Reviewed-on: https://go-review.googlesource.com/c/build/+/175141
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>

golang/build,golang/build,golang/build,golang/build