Remove unnecessary assertions from before block

What does this MR do?

Hopefully closes #119295 (closed).

There were assertions in the before block, and the test was intermittently failing on CI (only) exactly on the removed assertions. This MR removes them since assertions should happen in the it block, and the idea is to monitor this test without the unnecessary assertions to see if this fixes the intermittent issue.

Also, just to leave the code a bit cleaner than I found it, I have removed an unnecessary variable that was defined but used only once, so I moved its value to where it was used, and the variable itself is not needed anymore.

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

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