[dev.typeparams] cmd/compile: don't print out node pointer in ir.Dump

This has been a part of the node dumping since the very beginning, but
this makes diffing -W output pretty annoying. -d=dumpptrs already prints
these out if needed.

Change-Id: I9524a7f7b44ec780ae42a8a2a9588f11ab3950f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/340253


Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>