Ceph RGW bucket size reported as 0 in listBuckets/cmk despite non-zero RGW usage

### problem

When using Ceph RGW as Object Storage in CloudStack, bucket size is sometimes reported as 0 in CloudStack responses, even though the bucket has objects and RGW usage is non-zero.

S3 bucket contains objects and total data is about 1.43 GB.
RGW Admin listBucketInfo returns:
size_kb: 1499662
bytes equivalent: 1535653888
CloudStack listBuckets/cmk still shows size = 0 for that bucket.

s3cmd du -H s3://test-size-bucket/
1254M 11 objects s3://test-size-bucket/

cmk list buckets listall=true

{
"accesskey": "Hide",
"account": "Hide,
"created": "2026-05-22T13:13:17+0000",
"encryption": false,
"id": "2f612714-94dd-4ceb-8947-6f4cfcaeca05",
"name": "test-size-bucket",
"objectlocking": false,
"objectstorageid": "Hide,
"objectstore": "ceph",
"provider": "Ceph",
"quota": 100,
"size": 0,
"state": "Created",
"tags": [],
"url": "Hide",
"usersecretkey": "hide",
"versioning": false
}
],

Additional observation:
Bucket usage records are also never generated in my environment. I am not sure whether this is directly related, but it may share the same root cause.

### versions

cloudstack 4.22.1
Object Storage provider: Ceph RGW
Ceph release: Squid

### The steps to reproduce the bug

How to reproduce:

Configure Ceph RGW as Object Storage in CloudStack.
Create a bucket and upload multiple objects.
Verify bucket usage directly in Ceph/S3 tools (non-zero).
Run CloudStack bucket listing:
API: listBuckets
CLI: cmk list buckets listall=true
Observe bucket size in response.
Expected behavior:

Bucket size returned by CloudStack should reflect actual bucket usage (non-zero, consistent with RGW usage).
Actual behavior:

CloudStack returns size = 0 for bucket(s) that have data.

### What to do about it?

_No response_