[sssd PR#5228][comment] Test: Add back removed tests

[ikerexxe]

URL: https://github.com/SSSD/sssd/pull/5228
Title: #5228: Test: Add back removed tests

ikerexxe commented:
"""
test_users_by_filter_valid() was restored in [da79bee](https://github.com/SSSD/sssd/commit/da79bee1472a06b89be2df903fb0bd8ce600c610) and in [a6a5a08](https://github.com/SSSD/sssd/commit/a6a5a08a357d2adbb653b81bacc602ca3543c4c4). While test_groups_by_filter_valid() was restored in [fe6dd66](https://github.com/SSSD/sssd/commit/fe6dd669d1e8606862879127f92c177bb7fdc1bd) and in [16212bb](https://github.com/SSSD/sssd/commit/16212bbb2aaa55d0587515e72c0018479ae51be9).

That's why [issue 3920](https://github.com/SSSD/sssd/issues/3920) only mentions test_users_by_filter_multiple_domains_valid() and test_groups_by_filter_multiple_domains_valid().
"""

See the full comment at https://github.com/SSSD/sssd/pull/5228#issuecomment-661704836