Remove deprecated Ruby extension (devcontainers#894)

* Replace deprecated Ruby extension

* Remove the extension since the feature is already installing it

* Update devcontainer.json

Author: joshaber

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"
 }