doc/go1.19: delete remaining TODOs

doc/go1.19: delete remaining TODOs

The crypto ones were done in a separate CL and didn't merge well.
Same for runtime/debug.

The others are stale.

For #51400.

Change-Id: Iadb4de94d21cd6a20f52277a1c3d7800a729b81e
Reviewed-on: https://go-review.googlesource.com/c/go/+/411115
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>