gh-126483: disable warnings filters mutation in concurrent test (GH-132694)

gh-126483: disable warnings filters mutation in concurrent test (GH-132694)

The `test_ssl_in_multiple_threads` test failed because `test_check_hostname_idn()`
modified the global warnings filters via `warnings_helper.check_no_resource_warning()`.
Only check for warnings when the context aware warnings feature is enabled, which makes
the warnings filter context-local and thread-safe.