[release-branch.go1.21] crypto/tls: align FIPS-only mode with BoringSSL policy

This enables TLS 1.3, disables P-521, and disables non-ECDHE suites.

Updates #64717
Updates #62372
Fixes #64719

Change-Id: I3a65b239ef0198bbdbe5e55e0810e7128f90a091
Reviewed-on: https://go-review.googlesource.com/c/go/+/549975


Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/553856


Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>