test(kms): pin admin KMS response shapes where they are served (#5626)

The snapshots in crates/kms/src/api_types.rs pinned DeleteKeyResponse,
ListKeysResponse, DescribeKeyResponse and CancelKeyDeletionResponse, none
of which is serialized by any handler: those endpoints answer with
DeleteKmsKeyResponse and siblings in rustfs/src/admin/handlers/kms_keys.rs,
separate types carrying different fields. A breaking change to an admin
response could not fail them. Tag, untag and update-description had the
same gap, where the handler discards the kms-side response and serves its
own KmsKeyMetadataResponse.

Pin the shapes in the crate that produces them, and delete the four kms
mirrors. They were never in the pub use api_types list, had no
constructors and no callers, and only looked live because those snapshots
named them.

Keep the api_types snapshots that pin something real: configure, start,
stop and status are served verbatim by kms_dynamic, and the tag family
are live ObjectEncryptionService return types whose snapshots pin this
crate's public API rather than a wire shape.

crates/kms/src/snapshots/rustfs_kms__api_types__tests__kms_cancel_key_deletion_response.snap

@@ -1,9 +0,0 @@
----
-source: crates/kms/src/api_types.rs
-expression: "serde_json::to_value(CancelKeyDeletionResponse\n{\n    success: true, message: \"key deletion canceled\".to_string(), key_id:\n    \"key-a\".to_string(),\n}).expect(\"cancel deletion response should serialize\")"
----
-{
-  "key_id": "key-a",
-  "message": "key deletion canceled",
-  "success": true
-}

crates/kms/src/snapshots/rustfs_kms__api_types__tests__kms_delete_key_response.snap

@@ -1,10 +0,0 @@
----
-source: crates/kms/src/api_types.rs
-expression: "serde_json::to_value(DeleteKeyResponse\n{\n    success: true, message: \"key scheduled for deletion\".to_string(), key_id:\n    \"key-a\".to_string(), deletion_date:\n    Some(\"2026-07-01T00:00:00Z\".to_string()),\n}).expect(\"delete key response should serialize\")"
----
-{
-  "deletion_date": "2026-07-01T00:00:00Z",
-  "key_id": "key-a",
-  "message": "key scheduled for deletion",
-  "success": true
-}

crates/kms/src/snapshots/rustfs_kms__api_types__tests__kms_describe_key_response_missing.snap

@@ -1,9 +0,0 @@
----
-source: crates/kms/src/api_types.rs
-expression: "serde_json::to_value(DescribeKeyResponse\n{\n    success: false, message: \"key not found\".to_string(), key_metadata: None,\n}).expect(\"describe key response should serialize\")"
----
-{
-  "key_metadata": null,
-  "message": "key not found",
-  "success": false
-}

crates/kms/src/snapshots/rustfs_kms__api_types__tests__kms_list_keys_response.snap

@@ -1,14 +0,0 @@
----
-source: crates/kms/src/api_types.rs
-expression: "serde_json::to_value(ListKeysResponse\n{\n    success: true, message: \"keys listed\".to_string(), keys:\n    vec![\"key-a\".to_string(), \"key-b\".to_string()], truncated: true,\n    next_marker: Some(\"key-b\".to_string()),\n}).expect(\"list keys response should serialize\")"
----
-{
-  "keys": [
-    "key-a",
-    "key-b"
-  ],
-  "message": "keys listed",
-  "next_marker": "key-b",
-  "success": true,
-  "truncated": true
-}