Use os.MkdirAll, which is thread-safe (#849) (#850)

The same race condition does happen in the implementation of
os.MkdirAll[0], but that code there takes it into account and re-checks
the second error (the one on Mkdir), and it ends up returning nil if the
directory is indeed created, thus avoiding the race condition and making
os.MkdirAll thread-safe.

[0] https://github.com/golang/go/blob/e33f7c42b084182a3a88ef79857e33c11627159a/src/os/path.go#L19-L66

deployment/terraform/create.go

@@ -83,20 +83,7 @@ func New(id string, cfg deployment.Config) (*Terraform, error) {
 }
 
 func ensureTerraformStateDir(dir string) error {
-	// Make sure that the state directory exists
-	_, err := os.Stat(dir)
-	if err == nil {
-		return nil
-	}
-
-	// Return any error different than the one showing
-	// that the directory does not exist
-	if !errors.Is(err, os.ErrNotExist) {
-		return err
-	}
-
-	// If it does not exist, create it
-	return os.Mkdir(dir, 0700)
+	return os.MkdirAll(dir, 0700)
 }
 
 // Create creates a new load test environment.