Fixes for copier updates using renovate

chore(renovate): use upstream copier manager

Instead of our own regexManager implementation.

This was implemented in https://github.com/renovatebot/renovate/issues/25556 so we don't need our custom implmentation anymore and we can get rid of .copier-version in a separate MR.

To support this, we also need to set "allowScripts": true and "ignoreScripts": false to allow the copier upgrade scripts to run.

https://docs.renovatebot.com/configuration-options/#ignorescripts https://docs.renovatebot.com/self-hosted-configuration/#allowscripts

The copier.sh postUpgradeTask has been reduced to just run the update-asdf-version-variables.sh. Running copier update a second time would not do anything as the version in .copier-answers.yml has already been updated.