tests/image/ami: test ami images on AWS

Prior this commit the ami images were tested locally using qemu. This does
not reflect at all how they're used in practice. This commit introduces
the support for running them in the actual AWS. Yay!

The structure of code reflects that we want to switch to osbuild-composer
to build the images soon.

tools/test-case-generators/format-request-map.json

@@ -1,7 +1,7 @@
 {
   "ami": {
     "boot": {
-      "type": "qemu-extract"
+      "type": "aws"
     },
     "compose-request": {
       "distro": "",