Hardcoded InstanceID on connect-custom-bot sample

[MartinEzeLubo]

Describe the bug
The connect-custom-bot CDK deployment fails due to a hard-coded Amazon Connect Instance ID within the contact flow definition file. This prevents successful deployment when providing a different instance ID via parameters.

To Reproduce
Steps to reproduce the behavior:

1. Clone the repository
2. Navigate to samples/connect-custom-bot
3. Create a virtual environment: python3 -m venv .venv
4. Activate the virtual environment: source .venv/bin/activate
5. Install dependencies: pip install -r requirements.txt
6. Deploy the CDK stack using your Connect instance ID: cdk deploy --parameters instanceId=<YOUR_INSTANCE_ID>

Expected behavior
The CDK deployment should complete successfully without errors, using the provided instance ID instead of a hard-coded value.