Remove `compliance_framework_templates` feature flag

What does this MR do and why?

Graduates compliance framework templates to generally available by removing the compliance_framework_templates feature flag (gitlab_com_derisk, default-disabled, introduced in 19.0) and all of its gating, and graduates the complianceFrameworkTemplates GraphQL query field from experiment to GA.

Rollout work item: #596296 (closed)

Changes

• Backend: remove the Feature.enabled?(:compliance_framework_templates, …) guards from the framework-template resolver and the create-from-template mutation, and the push_frontend_feature_flag from the compliance dashboards controller. Access remains governed by authorize :admin_compliance_framework and the custom_compliance_frameworks licensed feature.
• GraphQL maturity: remove the experiment marker from the Query.complianceFrameworkTemplates field so it is now generally available; regenerated the GraphQL reference docs and the introspection schemas (public/-/graphql/introspection_result*.json).
• Frontend: the "Create from template" option in the new-framework wizard is now always shown (removed the glFeatures.complianceFrameworkTemplates gate and the now-unused feature-flag mixin).
• Flag definition: deleted the YAML definition.
• Specs: removed the now-obsolete "flag disabled" contexts (backend) and describe block (frontend).
• Docs: added the GA history entries and removed the feature-flag callouts in the user and GraphQL API docs.

Verification

• bundle exec rspec on the three affected request/graphql specs — 25 examples, 0 failures.
• yarn jest on method_step_spec.js — 3 passing.
• RuboCop, ESLint, markdownlint, vale, docs link check, and graphql_introspection_check — all green (pre-push).

Follow-ups (operational, outside this MR)

• After merge: /chatops gitlab run feature delete compliance_framework_templates --dev --pre --staging --staging-ref --production
• Close the feature issue #591059 (closed)