fix (plg_backend_azure): edge case on azure

There was this issue on azure where it would report through the browser
context cancelled error where the context we got back was stale as it
would get wrapped in utils.Wrap and cause downstream issues

server/plugin/plg_backend_azure/index.go

@@ -36,9 +36,7 @@ func (this *AzureBlob) Init(params map[string]string, app *App) (IBackend, error
 		Log.Debug("plg_backend_azure::new_client_error %s", err.Error())
 		return nil, ErrAuthenticationFailed
 	}
-	this.ctx = app.Context
-	this.client = client
-	return this, nil
+	return &AzureBlob{client, app.Context}, nil
 }
 
 func (this *AzureBlob) LoginForm() Form {