Remove some ci_workflow_rules_variables FF checks

What does this MR do?

We had an incident about the feature flag rollout because it was enabled by 10% of occurrences without any actor. So inconsistent behaviors happened. In this MR, we are removing unnecessary checks of the FF and add an actor to the FF.

Copy from comment (#327117 (comment 546704890))

For the specific case of the MR, I think we don't need to check the feature flag in:

• lib/gitlab/web_ide/config/entry/terminal.rb => job_variables
• lib/gitlab/ci/config/normalizer/matrix_strategy.rb => job_variables
• lib/gitlab/ci/config/entry/processable.rb => job_variables, root_variables_inheritance

So that we could add the project scope to other FF checking places as we have enough information.

from the @ayufan's comment =>

I don't think that we need FF check here, as we already to .compact, and we already do FF check on job.

Previous MR: !52085 (merged)

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• 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
• Security reports checked/validated by a reviewer from the AppSec team

Related to #294232 (closed)