Skip sleep in VCR replaying mode

In `SleepInSecondsForTest()`, skip the sleep when `VCR_MODE` is
`REPLAYING`. This makes the assumption that the sleep is always related
to a condition that's already mitigated by the fact that we're using
prerecorded fixtures, but it could be extended later to override this
behavior if necessary.

Fixes hashicorp/terraform-provider-google#20916

Author: wyardley

mmv1/third_party/terraform/acctest/resource_test_utils.go

@@ -90,7 +90,11 @@ func SkipIfVcr(t *testing.T) {
 
 func SleepInSecondsForTest(t int) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
-		time.Sleep(time.Duration(t) * time.Second)
+		// Assume we never want to sleep when we're in replaying mode.
+		vcrMode := os.Getenv("VCR_MODE")
+		if vcrMode == "REPLAYING" {
+			time.Sleep(time.Duration(t) * time.Second)
+		}
 		return nil
 	}
 }