cmd/link/internal/ld: re-enable DWARF tests on solaris/illumos

cmd/link/internal/ld: re-enable DWARF tests on solaris/illumos

It looks like these are fixed on current tip after CL 84655
marked them to be skipped.

Fixes #23168

Change-Id: I0020e6da1042f723eb54186ef0fe925df5326230
Reviewed-on: https://go-review.googlesource.com/c/go/+/349250
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>