Hi ianryde,
Make sure you have your latest backups in hand, be prepared to roll back to a pre-update state.
Now that you have a backup, go through the version update process. If the process hangs at the same place, leave it open in the browser.
Take the config file contents you have pasted above and copy them over the “empty” config.php and save that file.
Go back to the browser and refresh the stalled installer. Does the update complete?
I look forward to your reply!
Cheers,