test(runner): bound the last-action test by steps, not wall clock

100ms of wall clock against an assertion that two steps ran fatals under
load with "the web path never installed it", which reads as a
regression. every sibling test in the package uses a long duration and
MaxSteps.

internal/runner/web_last_action_test.go

@@ -50,7 +50,7 @@ func TestRunner_WebInstallsLastActionInThePage(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 	if _, err := Run(ctx, Options{
-		Duration:    100 * time.Millisecond,
+		Duration:    time.Hour,
 		IdleTimeout: 20 * time.Millisecond,
 		MaxSteps:    3,
 		Driver:      web,