feat(mcp): Add MCP data collection gating

[ericapisani]

Refs PY-2588
Refs #6748

[linear-code]

PY-2588

[github-actions]

Codecov Results 📊

✅ 104402 passed | ⏭️ 6677 skipped | Total: 111079 | Pass Rate: 93.99% | Execution Time: 360m 22s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +418
Passed Tests	📈 +418
Failed Tests	—
Skipped Tests	—

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2485 uncovered lines.
❌ Project coverage is 90.13%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
- Coverage    90.14%    90.13%    -0.01%
==========================================
  Files          193       193         —
  Lines        25147     25183       +36
  Branches      9136      9176       +40
==========================================
+ Hits         22669     22698       +29
- Misses        2478      2485        +7
- Partials      1431      1431         —

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Generated by Codecov Action

[sentry-warden]

MCP tool arguments leak to spans when send_default_pii=False

Tool arguments are only gated inside has_data_collection_enabled; when data_collection is not configured they are attached to spans unconditionally, bypassing the user's send_default_pii=False setting.

Evidence

• The test case no-data-collection-falls-back-to-send-default-pii sets expect_input=False for data_collection=None, send_default_pii=False, but the assertion if expect_input or data_collection is None forces the test to verify that arguments are still collected.
• In sentry_sdk/integrations/mcp.py, _tool_handler_wrapper only clears arguments inside if has_data_collection_enabled(client.options).
• When data_collection is not configured the code falls through to _set_span_input_data(span, ..., arguments, ...) with the original arguments dict, serializing potentially sensitive values into span data regardless of PII settings.

_{Identified by Warden · find-bugs · AF3-N8U}