Fix job trace download feature spec

What does this MR do and why?

Previously, when running this spec individually it failed.

See #391632 (comment 1286633235)

This commit makes this spec more resilient to changes related to request order.

How to set up and validate locally

1. On master run bin/rspec spec/features/projects/jobs_spec.rb:1067
2. See failure like described in #391632 (comment 1286633235)
3. On this branch run bin/rspec spec/features/projects/jobs_spec.rb:1067
4. The spec passes 💚

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.