Users of Azure Blob Storage, particularly those in China, may need to
customize the Azure endpoint. This change introduces a
`azure_storage_domain` parameter to be passed in the connection storage
settings. By default, `blob.core.windows.net` will be used. Example
other mappings:

1. China: blob.core.chinacloudapi.cn
2. US Government: blob.core.usgovcloudapi.net
3. Germany: blob.cloudapi.de

This change requires Workhorse changes as well:
https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/575.
Otherwise, the default domain will be used.

Documentation is in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40693.