Remove ability to create new service templates

What does this MR do?

This MR is an iteration towards Service Template deprecation, as we prepare for complete removal of Service Templates in %14.0 (#325196 (closed) and &5672 (closed))

This MR:

• updates the Service Templates page to only display active service templates. This effectively means that users can no longer create service templates
• adds a non-dimissible alert that describes service template deprecation
• updates/adds/removes specs based on the above changes.

Screenshots (strongly suggested)

No Active service templates	With active service template	Service template form

Does this MR meet the acceptance criteria?

Conformity

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