📦 Use raw image format for AWS

Although the vhdx format is smaller than raw, AWS often has some issues
booting instances from an imported vhdx snapshot. The raw format seems
to boot consistently at AWS.

Fixes #754.

Signed-off-by: Major Hayden <major@redhat.com>

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

@@ -8,7 +8,7 @@
       "arch": "",
       "image-type": "ami",
       "repositories": [],
-      "filename": "image.vhdx",
+      "filename": "image.raw",
       "blueprint": {}
     }
   },