Remove referencing TokenWithIv model in the codebase [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

As a part of a clean up after first failed attempt to update crypto-helper class, we needed to be able to handle nonce that was created randomly and using static nonce. Since affected records were also fixed manually, we can now get rid of handling randomly created nonces and stop referring the model in the code (so we can remove this table as the next step).

Screenshots (strongly suggested)

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
• Security reports checked/validated by a reviewer from the AppSec team

Related to #322592 (closed)