test(s3): cover delete option defaults

[overtrue]

Summary

Recent rm --purge work added RustFS-specific delete request options, and the follow-up test PR already covered the S3 client defaults for batch deletes. One command-layer behavior was still untested: ordinary rm --force should not silently enable RustFS permanent deletion unless --purge is explicitly set.

Root Cause

The CLI wiring introduced DeleteRequestOptions and mapped --purge into force_delete, but the unit tests only asserted the positive purge = true path. That left a regression window where a future refactor could accidentally treat the long-standing --force flag as a permanent-delete signal.

Fix

This PR now covers both sides of the option mapping:

• purge = true enables force_delete
• force = true with purge = false keeps force_delete disabled

The production code is unchanged. The diff stays limited to focused tests around the recent delete-option work.

Validation

This checkout does not define a make pre-commit target, so I ran the repository's required Rust validation commands directly instead:

• cargo fmt --all --check
• cargo clippy --workspace -- -D warnings
• cargo test --workspace