Specify Azure custom domain in Go Cloud query string

In https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40694, we made
some changes to the Workhorse direct upload API to support custom
domains in Azure.

While this worked, it made it quite complicated for Workhorse to handle
since the Go Cloud library (https://gocloud.dev/howto/blob/) expects all
the object store information to be available in a single URL.

To simplify this, we added a custom storage domain as a `domain` query
parameter in
https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/593.

lib/object_storage/direct_upload.rb

@@ -98,16 +98,19 @@ module ObjectStorage
         RemoteTempObjectID: object_name,
         ObjectStorage: {
           Provider: 'AzureRM',
-          AzureConfig: {
-            StorageDomain: config.azure_storage_domain
-          },
           GoCloudConfig: {
-            URL: "azblob://#{bucket_name}"
+            URL: azure_gocloud_url
           }
         }
       }
     end
 
+    def azure_gocloud_url
+      url = "azblob://#{bucket_name}"
+      url += "?domain=#{config.azure_storage_domain}" if config.azure_storage_domain.present?
+      url
+    end
+
     def use_workhorse_s3_client?
       return false unless Feature.enabled?(:use_workhorse_s3_client, default_enabled: true)
       return false unless config.use_iam_profile? || config.consolidated_settings?

spec/lib/object_storage/direct_upload_spec.rb

@@ -211,8 +211,7 @@ RSpec.describe ObjectStorage::DirectUpload do
         expect(subject[:UseWorkhorseClient]).to be true
         expect(subject[:RemoteTempObjectID]).to eq(object_name)
         expect(subject[:ObjectStorage][:Provider]).to eq('AzureRM')
-        expect(subject[:ObjectStorage][:AzureConfig][:StorageDomain]).to eq(storage_domain)
-        expect(subject[:ObjectStorage][:GoCloudConfig]).to eq({ URL: "azblob://#{bucket_name}" })
+        expect(subject[:ObjectStorage][:GoCloudConfig]).to eq({ URL: gocloud_url })
       end
     end
 
@@ -399,6 +398,7 @@ RSpec.describe ObjectStorage::DirectUpload do
       let(:has_length) { false }
       let(:storage_domain) { nil }
       let(:storage_url) { 'https://azuretest.blob.core.windows.net' }
+      let(:gocloud_url) { "azblob://#{bucket_name}" }
 
       it_behaves_like 'a valid AzureRM upload'
       it_behaves_like 'a valid upload without multipart data'
@@ -406,6 +406,7 @@ RSpec.describe ObjectStorage::DirectUpload do
       context 'when a custom storage domain is used' do
         let(:storage_domain) { 'blob.core.chinacloudapi.cn' }
         let(:storage_url) { "https://azuretest.#{storage_domain}" }
+        let(:gocloud_url) { "azblob://#{bucket_name}?domain=#{storage_domain}" }
 
         before do
           credentials[:azure_storage_domain] = storage_domain