[dev.typeparams] test: run all errorcheck tests that pass compiler with -G flag

Replace existing ad-hoc file exclusion mechanism with list of
excluded files; i.e., files for which the compiler with -G
option doesn't produce matching error messages yet.

Remove -G option since we now always run all passing tests.

Change-Id: I0655d2cf8bc135b3f50b1a811b8f49090c427580
Reviewed-on: https://go-review.googlesource.com/c/go/+/275212


Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>