fix FIPS mode compatibility

[Pectojin]

When using the zabbix_api.py script, in Ansible zabbix_host module, on a RHEL8 machine, with FIPS mode enabled, the following error is produced:
Failed to connect to Zabbix server: [digital envelope routines: EVP_DigestInit_ex] disabled for FIPS

The issue occurs on line 203, where the password is MD5 hashed before being printed to debug log:

        # don't print the raw password.
        hashed_pw_string = "md5(" + hashlib.md5(l_password.encode('utf-8'), usedforsecurity=False).hexdigest() + ")"
        self.debug(logging.DEBUG, "Trying to login with %s:%s" %
                (repr(l_user), repr(hashed_pw_string)))

Since the MD5 sum is only used for the debug log the simple options are to:

1. Indicate it's not used for security
2. Avoid printing the password to debug mode in any form

This PR accomplishes # 1

Issue is similar to s3tools/s3cmd#1005