[dev.typeparams] cmd/compile: remove outdate TODO in escape analysis

We now understand the root cause of #47227, it will be fixed in #47317.

Change-Id: Ifcd44f887a0bd3195818df33e409bd3e818e0b27
Reviewed-on: https://go-review.googlesource.com/c/go/+/336610


Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>