Make more intelligent use of the cache

Bust cache on the dynamic files
Use the cached builds for both virtualbox and Hyper-V
Hopefully improve loop downloading files to cache

distros/debian/11/amd64.pkrvars.hcl

@@ -1,8 +1,8 @@
 distro  = "debian"
 version = "11"
 iso = {
-  url      = "http://cdimage.debian.org/cdimage/archive/11.8.0/amd64/iso-cd/debian-11.8.0-amd64-netinst.iso"
-  checksum = "d7a74813a734083df30c8d35784926deaa36bc41e5c0766388e9f591ab056b72"
+  url      = "https://cdimage.debian.org/cdimage/archive/11.9.0/amd64/iso-cd/debian-11.9.0-amd64-netinst.iso"
+  checksum = "01c540225250d42cda3809d7130d0c27e934c8aca260d01a86d33dee19623b0f"
 }
 boot_command = [
  "<down>e<wait><down><down><down><end><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs>",