test(s3): cover delete wrapper defaults

[overtrue]

Summary

This PR adds focused unit coverage for the legacy ObjectStore delete wrappers in the S3 client. The recent force-delete work introduced options-aware delete helpers and tests around *_with_options, but the wrapper methods that existing call sites still use did not have direct coverage proving they delegate through the default option path.

Problem

Without a wrapper-level assertion, a future refactor could accidentally bypass the default options path and start sending the RustFS force-delete header for normal deletes. That would silently change ordinary delete behavior from delete-marker creation to permanent deletion on versioned buckets.

Root Cause

The original test additions validated explicit option handling, including force-delete header emission and omission on the *_with_options methods. The ObjectStore trait implementation methods delete_object and delete_objects now delegate into those helpers, but there was no regression test pinning that delegation.

Fix

The change adds two S3 client unit tests that call the wrapper methods directly and capture the generated HTTP requests. Each test asserts that the x-rustfs-force-delete header is absent when the wrapper uses default request options.

Validation

I first ran the two new unit tests directly:

• cargo test -p rc-s3 delete_object_wrapper_uses_default_options_without_rustfs_header
• cargo test -p rc-s3 delete_objects_wrapper_uses_default_options_without_rustfs_header

I then ran the repo's CI-equivalent checks:

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

make pre-commit was also requested by the automation prompt, but this checkout does not contain a Makefile or a pre-commit target, so I used the commands defined in .github/workflows/ci.yml instead.