[3.12] gh-129269: Exclude everything in sys.path in `test_coverage_ignore` (gh-130133) (gh-130358)

The `test_trace.test_coverage_ignore` test would fail if you had
`setuptools` installed, such as in `~/.local/lib/python3.xxx/site-packages/`.
Ignore everything in `sys.path` when running the test.
(cherry picked from commit 35925e952911aba97bfdaee85b09d734ceac4fea)