macOS Utility UI: Doesn't respect custom port when launching admin console from menu

## Description

If the chttpd port is set to something else, the macOS utility still tries to open 127.0.0.1:5984 in the browser.

## Steps to Reproduce

1. Change port to 5985
2. Click "Open Admin Console"

## Expected Behaviour

Open Fauxton browser window with correct port.

## Your Environment

macOS 12.0, CouchDB 3.2.0 (but has been around a lot longer).

Start at the macOS utility's “Open Admin Console” menu action and trace how it builds the browser URL; check how the configured chttpd port is obtained. Reproduce with port 5985 and confirm the Fauxton window opens at 127.0.0.1:5985 rather than :5984.

Written by the indexing model from the issue text.