[ROCm][CI] Fix qwen3tts file missing error

[tjtanaa]

PLEASE FILL IN THE PR DESCRIPTION HERE ENSURING ALL CHECKLIST ITEMS (AT THE BOTTOM) HAVE BEEN CONSIDERED.

Purpose

Fix

https://buildkite.com/vllm/vllm-omni-amd-ci/builds/4119/steps/canvas?sid=019d25a9-8bac-45e8-a29a-a4218557156f&tab=output

collecting ... ERROR: file or directory not found: tests/e2e/online_serving/test_qwen3_tts.py

By aligning the command in CUDA test pipeline test-ready.yml.

Test Plan

Trigger on CI.

Test Result

https://buildkite.com/vllm/vllm-omni-amd-ci/builds/4127/steps/canvas (in progress)

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan. Please provide the test scripts & test commands. Please state the reasons if your codes don't require additional test scripts. For test file guidelines, please check the test style doc
• The test results. Please paste the results comparison before and after, or the e2e results.
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model. Please run mkdocs serve to sync the documentation editions to ./docs.
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