Remove deprecated Ruby extension (#894)

* Replace deprecated Ruby extension

* Remove the extension since the feature is already installing it

* Update devcontainer.json

src/ruby/.devcontainer/devcontainer.json

@@ -18,22 +18,6 @@
  "ppa": "false"
  }
  },
- // Configure tool-specific properties.
- "customizations": {
- // Configure properties specific to VS Code.
- "vscode": {
- // Add the IDs of extensions you want installed when the container is created.
- "extensions": [
- "rebornix.Ruby"
- ]
- }
- },
- // Use 'forwardPorts' to make a list of ports inside the container available locally.
- // "forwardPorts": [],
-
- // Use 'postCreateCommand' to run commands after the container is created.
- // "postCreateCommand": "ruby --version",
-
  // Set `remoteUser` to `root` to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
  "remoteUser": "vscode"
 }