fixup! test: regenerate testvm01 with correct boot device

Regenerate testvm01 configuration using updated create-host templates:
- Boot device now /dev/vda (was /dev/sda)
- Imports ../template2/hardware-configuration.nix (was ../template)

This should fix the GRUB installation error during bootstrap.

Manually restored flake_branch field in terraform/vms.tf since create-host
doesn't manage that field yet.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

hosts/testvm01/configuration.nix

@@ -7,16 +7,15 @@
 
 {
   imports = [
-    ../template/hardware-configuration.nix
+    ../template2/hardware-configuration.nix
 
     ../../system
     ../../common/vm
   ];
 
   nixpkgs.config.allowUnfree = true;
-  # Use the systemd-boot EFI boot loader.
   boot.loader.grub.enable = true;
-  boot.loader.grub.device = "/dev/sda";
+  boot.loader.grub.device = "/dev/vda";
 
   networking.hostName = "testvm01";
   networking.domain = "home.2rjus.net";