"""Check if the policy string is a URL.

This function parses the input string using `urllib.parse.urlparse` and checks if the scheme is either 'http' or 'https'. If the parsing fails or the scheme is not valid, the function returns False.

Args:
    policy_string (str): The string to be checked for being a URL.

Returns:
    bool: True if the string is a valid URL with 'http' or 'https' scheme, False otherwise.
"""