gopls/internal/regtest/bench: don't run the iwl test with -short

The new InitialWorkspaceLoad benchmark relies on a memstats command that
does not exist in the released version of gopls (v0.11.0). We're
configuring x/benchmarks to run with -short, so use this to guard
against breaking the benchmark suite with this new test.

Change-Id: I64e673fca793c51bd17d0245330543402fd86ec8
Reviewed-on: https://go-review.googlesource.com/c/tools/+/473677
Reviewed-by: Alan Donovan <adonovan@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

gopls/internal/regtest/bench/iwl_test.go

@@ -16,6 +16,11 @@ import (
 // BenchmarkInitialWorkspaceLoad benchmarks the initial workspace load time for
 // a new editing session.
 func BenchmarkInitialWorkspaceLoad(b *testing.B) {
+	if testing.Short() {
+		// TODO(rfindley): remove this skip once the released gopls version
+		// supports the memstats command.
+		b.Skip("temporarily skipping as baseline gopls versions do not support the memstats command")
+	}
 	tests := []struct {
 		repo string
 		file string