js: Replace removed Meta.quit()

This one was moved to Meta.Context as well.

I don't know why the `debugexit` command quit with an error code
(it dates back all the way to commit 98bd590a5d). Terminating on
request by the user doesn't sound like an error, so don't replicate
that particular behavior.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1917>

js/ui/runDialog.js

@@ -42,7 +42,7 @@ class RunDialog extends ModalDialog.ModalDialog {
             // Developer brain backwards compatibility
             'restart': this._restart.bind(this),
 
-            'debugexit': () => Meta.quit(Meta.ExitCode.ERROR),
+            'debugexit': () => global.context.terminate(),
 
             // rt is short for "reload theme"
             'rt': () => {