disable_legacy_key_id missing from chart ConfigMap

[harrygodwin10]

I've been having an issue with registry v3 and the docker_auth Helm chart which I believe to be due to the fact that token.disable_legacy_key_id: true is required, per #401, but this setting is missing from the ConfigMap: https://github.com/cesanta/docker_auth/blob/main/chart/docker-auth/templates/configmap.yaml

This should be a very small PR, I should be able to raise one later this week, but I'm mentioning this in case someone else comes across it in the meantime!

[joshrivers]

I lost a week of progress due to this (and my distraction and incomplete flux/helm skills). Thank you for reporting this and providing a fix!

As an aside, it might be worth renaming this parameter in a future full release. It seems clear that in the near future this should be the default, not an override. Inverting the parameter name (revert_to_legacy_key_id) or configuring it with an enumeration (token_key_id_format: [v2|v3]) or the like might be better, long term. I figure this is more of a maintainer question than a feature request, and I'm happy either way, so I figured I'd just drop a note here rather than cluttering with a separate (perhaps unwanted) issue.

Again, thank you Harry!