Remove ruby debug adapter (#33541)

Now that the extension version has been bumped we can remove our in-tree
one to avoid having duplicate debug adapters.

Release Notes:

- The ruby debug adapter has been moved to the [ruby
extension](https://github.com/zed-extensions/ruby), if you have any
saved debug scenarios you'll need to change `"adapter": "Ruby"` to
`"adapter": "rdbg"`.

crates/debugger_ui/src/tests/new_process_modal.rs

@@ -267,7 +267,6 @@ async fn test_dap_adapter_config_conversion_and_validation(cx: &mut TestAppConte
         "Debugpy",
         "PHP",
         "JavaScript",
-        "Ruby",
         "Delve",
         "GDB",
         "fake-adapter",