Remove duplicate vscode settings from devcontainer

Settings that are in the .vscode/settings.json are already in use in the
devcontainer without them having to be set also in the
devcontainer.json.

.devcontainer/devcontainer.json

@@ -16,14 +16,7 @@
                 "github.vscode-github-actions",
                 "ms-python.black-formatter",
                 "ms-python.mypy-type-checker"
-            ],
-            "settings": {
-                "python.testing.unittestEnabled": false,
-                "python.testing.pytestEnabled": true,
-                "[python]": {
-                    "editor.defaultFormatter": "ms-python.black-formatter"
-                }
-            }
+            ]
         }
     }
 }