Only fetch issue template names when actually editing an issue
Issues can have templates stored in the repository: https://docs.gitlab.com/ee/user/project/description_templates.html
We store the names of the templates in Redis to avoid having to fetch the template name list for the dropdown from the git repository every time someone creates or edits an issue.
Because the edit page on issues is inline (not a separate page load), we load the template names whenever we load an issue for viewing.
However, changing to use a different template in an issue is relatively uncommon compared to actually looking at the issue.
https://dashboards.gitlab.net/d/rPsQXrImk/rails-controller?orgId=1&refresh=1m&var-env=gprd&var-type=web&var-stage=main&var-controller=Projects::TemplatesController&var-action=All shows that actually loading a template is a very rare operation.
https://dashboards.gitlab.net/d/rPsQXrImk/rails-controller?orgId=1&refresh=1m&var-env=gprd&var-type=web&var-stage=main&var-controller=Projects::IssuesController&var-action=show&var-action=update.json shows that viewing and editing issues are common.
Therefore I think we should only load the template names async when you actually click to edit an issue. This will save us a Redis hit per issue view, which isn't much, but it is something that's completely unnecessary as it stands.