ipatests: Skip the test failing due to FIPS policy
    
    1. test_certmonger_reads_token_HSM test in test_installaton.py
    is failing in FIPS/STIG mode with the below error.
    
    SEC_ERROR_PKCS12_UNABLE_TO_IMPORT_KEY: Unable to import.
    Error attempting to import private key in STIG mode
    
    2. Adding the posfix config change, because there was a crash
    seen in smtpd in FIPS mode.
    
    ie. postconf -e smtpd_tls_fingerprint_digest=sha256
    
    KCS: https://access.redhat.com/solutions/6958957
    
    Signed-off-by: Sudhir Menon <sumenon@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>