[CI][SM70] Fix #346 benchmark regex imports

[yangzhuxinyzx]

Purpose

Repair the changed-file static gate found while auditing #346. The two new SM70 benchmark modules used the forbidden stdlib re import; repository policy requires regex as re.

Test Plan

• Run pre-commit on both changed benchmark files.
• Re-run all changed-file pre-commit hooks on the [Bugfix][SM70] Audit DFlash2 output quality #346 integration audit tree.
• Parse all three new benchmark CLIs with --help.

Test Result

• Two-file pre-commit: passed, including ruff, mypy, SPDX, forbidden-import and configuration gates.
• Full [Bugfix][SM70] Audit DFlash2 output quality #346 changed-file pre-commit after this patch: passed.
• benchmark_sm70_tool_datasets.py --help: passed.
• benchmark_sm70_tool_protocol.py --help: passed.
• compare_sm70_dflash2_quality_matrix.py --help: passed.

Base head audited: f5a93e2de2f1940de0e498afb01db85b77982948.
Repair head: be44103c65928d574701fdee452ed9fac084e07c.