Bound ListingTable metadata requests for explicit file lists

[osipovartem]

Summary

• Bound initial ListingTable metadata/list requests by the existing meta_fetch_concurrency setting instead of polling every explicit path at once.
• Preserve path ordering, downstream bounded flattening, and error propagation.

Verification

• cargo +1.97.0 test -p datafusion-catalog-listing --lib --profile ci (20 passed)
• cargo +1.97.0 fmt -p datafusion-catalog-listing --check
• Independent read-only review: approved; no blocking issues. A request-counting ListingTable integration test remains a non-blocking coverage improvement.