chore(ecstore): remove dead MinIO-port client modules (~940 lines) (#5982)

Delete five zero-caller client modules (api_bucket_policy,
api_get_object_acl, api_get_object_attributes, api_get_object_file,
api_restore), the orphaned TransitionCore get/put_bucket_policy
wrappers, and the two constants only they consumed. Also removes two
unwrap() panics on remote-controlled data in api_get_object_acl.rs
(non-UTF-8 body, missing Owner ID). Tier warm-backend APIs untouched.

Ref: rustfs/backlog#1822 (T1)

crates/ecstore/src/client/constants.rs

@@ -37,6 +37,3 @@ pub const TOTAL_WORKERS: i64 = 4;
 pub const SIGN_V4_ALGORITHM: &str = "AWS4-HMAC-SHA256";
 pub const ISO8601_DATEFORMAT: &[FormatItem<'_>] =
     format_description!("[year]-[month]-[day]T[hour]:[minute]:[second].[subsecond]Z");
-
-pub const GET_OBJECT_ATTRIBUTES_TAGS: &str = "ETag,Checksum,StorageClass,ObjectSize,ObjectParts";
-pub const GET_OBJECT_ATTRIBUTES_MAX_PARTS: i64 = 1000;