[DRAFT] Type sentry.snuba.metrics.query_builder and remove override

[cursor]

Summary

• remove sentry.snuba.metrics.query_builder from the mypy "typing issues" override list in pyproject.toml
• fix all mypy errors in src/sentry/snuba/metrics/query_builder.py by tightening type narrowing and adding safe parameter coercion helpers
• keep behavior unchanged while making the module pass strict typing without disable_error_code overrides

Validation

• PATH="/workspace/.venv/bin:$PATH" .venv/bin/python -m tools.mypy_helpers.mypy_without_ignores src/sentry/snuba/metrics/query_builder.py ✅
• SENTRY_MYPY_PRE_PUSH=1 .venv/bin/prek run -q mypy --files src/sentry/snuba/metrics/query_builder.py --stage pre-push ✅
• .venv/bin/prek run -q ✅
• make test-selective ⚠️ failed in this environment because gcloud is not installed
• SENTRY_SKIP_SERVICE_VALIDATION=1 .venv/bin/pytest -n3 -svv --reuse-db tests/sentry/snuba/metrics/test_query_builder.py ⚠️ failed because Redis/Docker services are unavailable (Connection refused localhost:6379)

@armenzg could you please review this draft PR?

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.