Move test_remove_unused_code to Quarantine

[kaxil]

This test is passing locally and on breeze. Not sure of a reason why it is failing on CI

---

Make sure to mark the boxes below before creating PR: [x]

• Description above provides context of the change
• Unit tests coverage for changes (not needed for documentation changes)
• Target Github ISSUE in description if exists
• Commits follow "How to write a good git commit message"
• Relevant documentation is updated including usage instructions.
• I will engage committers as explained in Contribution Workflow Example.

---

In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in UPDATING.md.
Read the Pull Request Guidelines for more information.

[mik-laj]

I don't know if it's a good idea to add non-working tests to quarantine. The quarantine should contain tests that do not behave stable and it is necessary to test their behavior before fixing them. However, this may be a workaround.