RemovedInDjango51Warning for get_storage_class image_helpers

[awais786]

The get_storage_class function was removed in Django 5.1:

https://docs.djangoproject.com/en/5.2/releases/5.1/#features-removed-in-5-1

edx-platform/openedx/core/djangoapps/user_api/accounts/image_helpers.py

Line 11 in 9750c63

from django.core.files.storage import get_storage_class

Example fix in edx-platform PR #36628
Reference implementation in edx-val commit

Notes:

• Ensure the updated code is compatible with both Django 4.2 and Django 5.2.
• Add or update relevant unit tests to cover the changes.
• Verify functionality locally before merging ( course import export from studio )
• If feasible, implement future-compatible code that also checks for a backend defined under the course_metadata_exports key in the STORAGES dictionary. Although this key is not currently present in production, adding this check now will enable seamless migration when such storage configurations are introduced in the future.