cmd/gopherbot: don't autosubmit CLs with wait-release
cmd/gopherbot: don't autosubmit CLs with wait-release

If a CL has the "wait-release" hashtag set, don't autosubmit it, since
we are presumably in the freeze, and should wait for the tree to open.

Updates golang/go#48021
Updates golang/go#24836

Change-Id: I23258ccbb71d2b8febe97ad8883b9fe9f90c761d
Reviewed-on: https://go-review.googlesource.com/c/build/+/391734
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Trust: Roland Shoemaker <0d270388f2f92757a5de0f4bd891d3b392c44c4f@golang.org>
Run-TryBot: Roland Shoemaker <0d270388f2f92757a5de0f4bd891d3b392c44c4f@golang.org>
Auto-Submit: Roland Shoemaker <0d270388f2f92757a5de0f4bd891d3b392c44c4f@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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