Update test flatrate_conditions_material_tracking_spec

[metas-dh]

Test shall include:

• Customer Fixtures to use: (if needed)
• What to test
• Expectation for the test to be successful

flatrate_conditions_material_tracking_spec needs to be updated, so we can create Material Trackings for testing Karottenabrechnung.

Todo for developer (besides coding)

• Always make sure the issue is in the correct project lane
• [x] run your test in jenkins e2e on a vanilla db
  • dev669.metasfresh.com
• [x] jenkins console URL / cypress dashboard URL to the successful test suite run (not just yours)
  • https://dashboard.cypress.io/#/projects/5yp4q1/runs/616/specs
  • https://jenkins.metasfresh.com/job/ops/job/run_e2e_tests/734/console
• [x] get it integrated into master
  • [x] https://github.com/metasfresh/metasfresh-e2e/pull/359

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