ipatests: add missing tests to nightly run
    
    The following test suites were missing in nightly_ipa-4-6.yaml:
    - test_integration/test_crlgen_manage.py
    - test_integration/test_nfs.py
    - test_integration/test_otp.py
    
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>