Erase stale coverage before hatch test

[floze-the-genius]

Summary

• erase stale coverage data before running tests with coverage enabled
• use the patched coverage configuration so custom data-file settings are respected
• preserve custom test scripts and the existing quiet command output

Fixes #1984.

Validation

• hatch fmt --check
• hatch run types:check src/hatch/cli/test/__init__.py
• hatch test --python 3.14 -- tests/cli/test/test_test.py -q (34 passed)
• hatch test --python 3.14 --cover-quiet (2405 passed, 50 skipped)

AI assistance disclosure

OpenAI Codex was used extensively for repository analysis, implementation, regression-test updates, and validation.

[floze-the-genius]

The CI matrix failure is unrelated to this PR's coverage cleanup. Every failing platform stops in hatch run types:check on the same two unchanged plugin-hook errors (CustomEnvironmentCollector and CustomBuildHook). The latest completed master test run (29471760769) fails on those exact two mypy errors as well, so this is a current baseline failure rather than a regression in the three changed files.

[cjames23]

Thanks for contributing this!