Changes limit for terraform artifacts to 5MB

What does this MR do?

This is Configure's addition to !34767 (merged) which adds artifact file limits to plan_limits. This MR enables the limit for terraform artifacts and defaults it to 5MB. It also removes ci_max_artifact_size_terraform from the list of exclusions in the spec so that it will be checked by the tests added by !34767 (merged)

Closes https://gitlab.com/gitlab-org/gitlab/-/issues/220522

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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