test_runner: use separate directory for each rerun (#6004)

## Problem

While investigating https://github.com/neondatabase/neon/issues/5854, we
hypothesised that logs/repo-dir from the initial failure might leak into
reruns. Use different directories for each run to avoid such a
possibility.

## Summary of changes
- make each test rerun use different directories
- update `pytest-rerunfailure` plugin from 11.1.2 to 13.0

test_runner/fixtures/neon_fixtures.py

@@ -3029,6 +3029,11 @@ def get_test_output_dir(request: FixtureRequest, top_output_dir: Path) -> Path:
     """Compute the working directory for an individual test."""
     test_name = request.node.name
     test_dir = top_output_dir / test_name.replace("/", "-")
+
+    # We rerun flaky tests multiple times, use a separate directory for each run.
+    if (suffix := getattr(request.node, "execution_count", None)) is not None:
+        test_dir = test_dir.parent / f"{test_dir.name}-{suffix}"
+
     log.info(f"get_test_output_dir is {test_dir}")
     # make mypy happy
     assert isinstance(test_dir, Path)