Telegraf Controller: define canonical sources for duplicated authentication content

[jstirnaman]

Current state

On the telegraf-controller-ga branch, the following content appears in more than one page:

1. Authentication providers table (Local, LDAP, OIDC with availability and sign-in method):

   • content/telegraf/controller/authentication/_index.md
   • content/telegraf/controller/reference/authentication-authorization.md

   The two copies have already diverged: the Local provider's availability is "Free" in authentication/_index.md and "Free tier" in the reference page.

2. API token facts (tc-apiv1_ prefix, value shown once at creation, permissions bounded by the owning user's role):

   • content/telegraf/controller/tokens/_index.md
   • content/telegraf/controller/reference/authentication-authorization.md

3. Authorization header example (Bearer/Token scheme with a tc-apiv1_ token):

   • content/telegraf/controller/tokens/use.md
   • content/telegraf/controller/reference/api.md (docs(controller): add Telegraf Controller API reference page #7314)

Recommended changes

For each item, designate one page as the canonical source and update the other pages to either link to it or transclude it:

• Decide whether the task page or the reference page owns each fact.
• Replace non-canonical copies with a link, or extract the content into a shared file per the shared content guidance.
• Reconcile the "Free" / "Free tier" divergence in the providers table as part of the change.

Related

• docs(controller): add Telegraf Controller API reference page #7314 (API reference page)
• docs(controller): document authentication providers (Local, LDAP, OIDC) #7277 (authentication providers documentation)
• docs(controller): cross-link user sign-in and API token sections #7324 (cross-links between the authentication and tokens sections)