Don't run runtime tests in parallel.

We need real sharding, and will let Bazel handle the
parallelization. That is coming soon. Until then, remove
this call to t.Parallel() so that we can run the tests without
eating all CPU.

PiperOrigin-RevId: 264498919

test/runtimes/runtimes_test.go

@@ -49,8 +49,6 @@ func testLang(t *testing.T, lang string) {
 	for _, tc := range tests {
 		tc := tc
 		t.Run(tc, func(t *testing.T) {
-			t.Parallel()
-
 			d := testutil.MakeDocker("gvisor-test")
 			if err := d.Run(img, "--test", tc); err != nil {
 				t.Fatalf("docker test %q failed to run: %v", tc, err)