Remove the latest redirect feature flag for CI/CD templates

What does this MR do and why?

Removing the feature flag code for the latest template redirection. This dynamic flag was introduced for gauging Deployment.latest template impact, which has already been migrated in %14.0.

It'd be better to remove this flag in general by the following reasons:

• Dynamic flag reference is not a good practice in the current architecture. All flags should be statistically defined.
• It's hard to determine which version of template is taking effect currently.
• There is a little bit tweak required on specs.

Closes #361460 (closed)

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