Support for the virtual hosted style of S3 bucket address

[antonvigo]

Rancher Server Setup

• Rancher version: v2.11.3
• Installation option (Docker install/Helm Chart): Helm Chart
• Kubernetes Version and Engine: 1.30 CCE (HuaweiCloud provider)

Describe the bug
It's not possible to use OBS - S3 analog from HuaweiCloud - as backup storage. The main reason it that since February 2025 OBS doesn't support path-style addresses any more (like obs.eu-west-101.myhuaweicloud.eu/some-bucket). Instead of this Virtual-hosted-style address should be used (e. g. some-bucket.obs.eu-west-101.myhuaweicloud.eu). And looks like there is no way to use the second option of address in backup object manifest. At least because of mandatory bucketName field and other limitaions.

To Reproduce
Steps to reproduce the behavior:

1. Create OBS in HuaweiCloud, put its credentials in k8s secret
2. Within Rancher UI go to: Rancher Backups -> Backups -> Create
3. Set such backup config:

apiVersion: resources.cattle.io/v1
kind: Backup
metadata:
  name: s3-recurring-backup
spec:
  storageLocation:
    s3:
      bucketName: rancher-backup
      credentialSecretName: rancher-backup-s3
      credentialSecretNamespace: default
      endpoint: obs.eu-west-101.myhuaweicloud.eu
      region: eu-west-101
  resourceSetName: rancher-resource-set-full
  schedule: "* */1 * * *"
  retentionCount: 3

4. Error message appears:

Failed to check if s3 bucket [rancher-backup] exists, error: Access Denied.

Expected behavior
Backup is done and backup file is transferred to specified S3.