Upgrade Velero to v1.15.0

[raviranjanelastisys]

Chart to upgrade

https://github.com/vmware-tanzu/velero/releases/tag/v1.14.1

Reason for upgrade

• [ ] Security patching
• [x] Upgrade to allow new features
• [x] Upgrade to prevent future issues
• [x] Upgrade to maintain a supported version
• [ ] Other - Write the reason below

Additional context

No response

Acceptance criteria

• I checked the migration of the new chart version:
  • [ ] The upgrade does not require migration steps
  • [ ] The upgrade requires migration steps
• I tested the functionality of the new chart version:
  • [ ] The upgrade does not change current functionality
  • [ ] The upgrade changes current functionality