test(mcp): Remove vacuous test_fastmcp_prompt_async()

[alexander-alderman-webb]

Description

The only assertion is trivially true because an HTTP server transaction is created.

Issues

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[github-actions]

Codecov Results 📊

✅ 130162 passed | ⏭️ 7118 skipped | Total: 137280 | Pass Rate: 94.81% | Execution Time: 481m 15s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -426
Passed Tests	📉 -422
Failed Tests	—
Skipped Tests	📉 -4

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2504 uncovered lines.
❌ Project coverage is 90.27%. Comparing base (36ff01e) to head (7692241).

Coverage diff

@@            Coverage Diff             @@
##        master       #PR       +/-##
==========================================
- Coverage    90.28%    90.27%    -0.01%
==========================================
  Files          193       193         —
  Lines        25729     25729         —
  Branches      9496      9496         —
==========================================
+ Hits         23228     23225        -3
- Misses        2501      2504        +3
- Partials      1432      1432         —

---

Generated by Codecov Action