Connection to redshift cluster doesn't show "Temporary Credentials" as an option

## Problem
Same as title

The "temporary credentials" auth option should be support by AWS Toolkit on VSCode according to this documentation: https://docs.aws.amazon.com/toolkit-for-vscode/latest/userguide/redshift-overview.html

## Steps to reproduce the issue
1. Refresh local credentials to connect to AWS
2. Go to 'Explorer' tab in the AWS Toolkit extension
3. (Optiona) Set region for the account
4. Select a cluster under 'Redshift'
5. The dropdown on the right should show 3 options: "Database user name and password", "AWS Secrets Manager" and "Temporary credentials". But "Temporary credentials" is not shown currently.

## Expected behavior
"Temporary credentials" should be shown as an option to connect to Redshift cluster

## System details (run `AWS: About` and/or `Amazon Q: About`)

- OS: Macos Seqouia 15.3
- Visual Studio Code version: 1.98.2
- AWS Toolkit version: 3.50.0
- Amazon Q version: 1.51.0

Start by reproducing the issue through the AWS Toolkit Explorer tab and the Redshift cluster connection dropdown, using the listed steps. Trace that connection flow and verify that the menu includes Database user name and password, AWS Secrets Manager, and Temporary credentials.

Written by the indexing model from the issue text.