feat: lower risk of undoing user changes when getting credentials

Using a plain "user.save()" runs the risk of undoing recent changes made by
other parts of the application. So we change this to use "update_fields" to
only change the field we are interested in, in this case tools_access_role_arn
that is used when a user access AWS resources directly.

This does not address a reported issue, just something I noticed.

dataworkspace/dataworkspace/apps/core/utils.py

@@ -1289,7 +1289,7 @@ def create_tools_access_iam_role(user_id, user_email_address, access_point_id):
 
     # Cache the role_arn so it can be retrieved in the future without calling AWS
     user.profile.tools_access_role_arn = role_arn
-    user.save()
+    user.profile.save(update_fields=['tools_access_role_arn'])
 
     return role_arn, s3_prefixes