[SSSD] [sssd PR#726][opened] TESTS: Add a simple integration test for retrieving the extraAttributes property

[jhrozek]

   URL: https://github.com/SSSD/sssd/pull/726
Author: jhrozek
 Title: #726: TESTS: Add a simple integration test for retrieving the extraAttributes
property
Action: opened

PR body:
"""
Related: https://pagure.io/SSSD/sssd/issue/3906
"""

To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/726/head:pr726
git checkout pr726