This PR extends the `tmpdir` class with an option to preserve the directory if the destructor is called during stack unwinding. It also uses this feature in KMIP tests, where the tmpdir contains PyKMIP server logs, which may be useful when diagnosing test failures.
Fixes#25339.
Not so important to be backported.
Closesscylladb/scylladb#25367
* github.com:scylladb/scylladb:
encryption_at_rest_test: Preserve tmpdir from failing KMIP tests
test/lib: Add option to preserve tmpdir on exception