lightning import supports analyze parameter tidb_build_sampling_stats_concurrency

## Feature Request

**Is your feature request related to a problem? Please describe:**
lightning currently doesn't support analyze paramter tidb_build_sampling_stats_concurrency, which might impact analyze speed.

**Describe the feature you'd like:**
support paramters for tidb_build_sampling_stats_concurrency

**Describe alternatives you've considered:**

**Teachability, Documentation, Adoption, Migration Strategy:**

Start by locating TiDB Lightning's analyze parameter handling and the existing parameter plumbing for import analysis. Confirm how tidb_build_sampling_stats_concurrency is passed through and verify that it affects analyze speed as intended; the issue names no files or tests, so the relevant entry points must first be identified.

Written by the indexing model from the issue text.