## Summary
When `STORAGE_IMPL=AWS_S3`, the Admin Service status page keeps showing
MinIO. Three things conspire:
1. `admin/server/config.py::load_configurations` only knows the
`minio` and `minio_0` config keys. An `s3` block lands on the
`case _:` branch and logs `Unknown configuration key: s3`
(issue #17294).
2. `admin/server/services.py::ServiceMgr.get_all_services` filters
retrieval services by `DOC_ENGINE` but has no equivalent filter
for `file_store` services by `STORAGE_IMPL`. A stale MinIO block
is returned regardless of the active backend.
3. The wired health check is hardcoded to `check_minio_alive`, which
calls `settings.MINIO['host']`. With `STORAGE_IMPL=AWS_S3` that
block is uninitialized, so the check always times out.
Fixes#17294
### What problem does this PR solve?
As title
### Type of change
- [x] Refactoring
Signed-off-by: Jin Hai <haijin.chn@gmail.com>
Co-authored-by: Zhichang Yu <yuzhichang@gmail.com>
