crypto/sha1: use cryptotest.TestAllImplementations and impl.Register

crypto/sha1: use cryptotest.TestAllImplementations and impl.Register

Not running TryBots on s390x because the new LUCI builder is broken.

Change-Id: I6a6a4656a8d52fa5ace9effa67a88fbfd7d19b04
Reviewed-on: https://go-review.googlesource.com/c/go/+/674915
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
Auto-Submit: Filippo Valsorda <filippo@golang.org>