cmd/dist: remove windows-amd64-2008 code path

`windows-amd64-2008` builder does no longer exist on go1.20,
so it is safe to remove conditions checking for that name.

Updates golang#57003
Closes golang#56904

Change-Id: I941ccc64cda0af3b9356996c4b581700afa81987
Reviewed-on: https://go-review.googlesource.com/c/go/+/467175
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

src/cmd/dist/test.go

@@ -1568,21 +1568,14 @@ func (t *tester) registerRaceTests() {
 		// t.registerTest("race:misc/cgo/test", hdr, &goTest{dir: "../misc/cgo/test", race: true, env: []string{"GOTRACEBACK=2"}})
 	}
 	if t.extLink() {
-		var oldWindows rtPreFunc
-		if strings.HasPrefix(os.Getenv("GO_BUILDER_NAME"), "windows-amd64-2008") {
-			oldWindows.pre = func(*distTest) bool {
-				fmt.Println("skipping -race with external linkage on older windows builder, see https://github.com/golang/go/issues/56904 for details")
-				return false
-			}
-		}
 		// Test with external linking; see issue 9133.
 		t.registerTest("race:external", hdr,
 			&goTest{
 				race:     true,
 				ldflags:  "-linkmode=external",
 				runTests: "TestParse|TestEcho|TestStdinCloseRace",
 				pkgs:     []string{"flag", "os/exec"},
-			}, oldWindows)
+			})
 	}
 }