Ensure group webhooks are always enabled

Spinning off from #1182 (comment 1486937016)

It's been an issue that webhooks in https://gitlab.com/gitlab-org we're using for the service can be auto-disabled. In the original issue we're talking about raising visibility when that happened. This issue focuses on making sure it's always enabled without human intervention.

Potential solutions

🍎 Product feature to make sure it'll self-heal: gitlab-org/gitlab#396577
🍊 Figuring out if there's any bugs to auto-disable webhooks, because it doesn't seem to add up that it should be auto-disabling it so often: gitlab-org/gitlab#396577 (comment 1433229017)
- Improve observability of the feature by adding logging: gitlab-org/gitlab!128212 (merged)
🍋 Use an owner token to automate re-enabling the webhooks:
- Periodically, or
- When we detected that it's likely going down
- We can do both!
🥝 Change the product so enabling group webhooks doesn't need to have owner permission, but maintainer permission, so we can use a maintainer token for this
🍇 Make it able to disable auto-disabling for this case