perf test: Clean up mypy and pylint issues in shell test libraries

Clean up mypy type errors and pylint errors/warnings in
tools/perf/tests/shell/lib/ (attr.py, perf_json_output_lint.py, and
perf_metric_validation.py):
- Fix E0606 (possibly-used-before-assignment) in perf_metric_validation.py
  by importing sys at module level.
- Add type annotations for stack, second_results, collectlist,
  get_bounds(), and main() in perf_metric_validation.py.
- Avoid assigning -1 to list[int] expected_items in
  perf_json_output_lint.py, rename shadowing variables, and remove
  redundant lambdas.
- Remove unnecessary semicolons, use lazy logging arguments, specify
  exception types and file encodings, and initialize module-level logger
  in attr.py.

Also update tools/perf/tests/shell/lib/setup_python.sh to:
- Avoid x-prefix string comparisons.
- Export PYTHON and resolve PYTHONPATH and PERF_EXEC_PATH from
  BASH_SOURCE[0], ../../../python (for nested test directories such as
  coresight/), and the directory containing the perf binary so out-of-tree
  builds and standalone perf python scripts work seamlessly.

Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions