"""Parse a database URI and extract connection parameters.

This function takes a database URI and parses it to extract essential connection
parameters such as host, port, database name, user, and password. The URI scheme
is simplified by removing any driver-specific parts (e.g., 'postgresql+pg8000' becomes 'postgresql').
If the port is not specified in the URI, it defaults to 5432.

Args:
    uri (str): The database URI to be parsed.

Returns:
    dict: A dictionary containing the connection parameters with keys 'host', 'port',
          'database', 'user', and 'password'.
"""