model: remove reading /cdrom/.disk/info

Since Curtin now has a builtin hook to copy over information from
/cdrom/.disk, it's uncessary to repeat it in Subiquity.

subiquity/models/subiquity.py

@@ -486,13 +486,6 @@ class SubiquityModel:
             os.makedirs(os.path.dirname(path), exist_ok=True)
             write_file(path, content, mode=mode)
 
-    def _media_info(self):
-        if os.path.exists("/cdrom/.disk/info"):
-            with open("/cdrom/.disk/info") as fp:
-                return fp.read()
-        else:
-            return "media-info"
-
     def _machine_id(self):
         with open("/etc/machine-id") as fp:
             return fp.read()
@@ -525,11 +518,6 @@ class SubiquityModel:
                     "content": self._machine_id(),
                     "permissions": 0o444,
                 },
-                "media_info": {
-                    "path": "var/log/installer/media-info",
-                    "content": self._media_info(),
-                    "permissions": 0o644,
-                },
             },
         }
 

subiquity/models/tests/test_subiquity.py

@@ -180,7 +180,6 @@ class TestSubiquityModel(unittest.IsolatedAsyncioTestCase):
         for model in model_no_proxy, model_proxy:
             config = model.render()
             self.assertConfigWritesFile(config, "etc/machine-id")
-            self.assertConfigWritesFile(config, "var/log/installer/media-info")
 
     def test_storage_version(self):
         model = self.make_model()