### Apache Airflow version

2.6.1

### What happened

This [PR](https://github.com/apache/airflow/pull/28187) introduced the get_iam_token method in `redshift_sql.py`. This is the breaking change as  introduces the check for `iam` in extras, and it's set to False by default.

Error log:
```

self = <airflow.providers.amazon.aws.hooks.redshift_sql.RedshiftSQLHook object at 0x7f29f7c208e0>
conn = redshift_default

    def get_iam_token(self, conn: Connection) -> tuple[str, str, int]:
        """
        Uses AWSHook to retrieve a temporary ***word to connect to Redshift.
        Port is required. If none is provided, default is used for each service
        """
        port = conn.port or 5439
        # Pull the custer-identifier from the beginning of the Redshift URL
        # ex. my-cluster.ccdre4hpd39h.us-east-1.redshift.amazonaws.com returns my-cluster
>       cluster_identifier = conn.extra_dejson.get("cluster_identifier", conn.host.split(".")[0])
E       AttributeError: 'NoneType' object has no attribute 'split'

.nox/test-3-8-airflow-2-6-0/lib/python3.8/site-packages/airflow/providers/amazon/aws/hooks/redshift_sql.py:107: AttributeError
```


### What you think should happen instead

It should have backward compatibility

### How to reproduce

Run an example DAG for redshift with the AWS IAM profile given at hook initialization to retrieve a temporary password to connect to Amazon Redshift.

### Operating System

mac-os

### Versions of Apache Airflow Providers

_No response_

### Deployment

Astronomer

### Deployment details

_No response_

### Anything else

_No response_

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

#
#
from __future__ import annotations
from functools import cached_property
from typing import TYPE_CHECKING
import redshift_connector
from redshift_connector import Connection as RedshiftConnection
from sqlalchemy import create_engine
from sqlalchemy.engine.url import URL
from airflow.providers.amazon.aws.hooks.base_aws import AwsBaseHook
from airflow.providers.common.sql.hooks.sql import DbApiHook
if TYPE_CHECKING:
    from airflow.models.connection import Connection
class RedshiftSQLHook(DbApiHook):