Fix Lab 4 - 'Advance RAG' notebook (4) existing bugs.

[avelizf]

Fixes include (1) update regions to us-west-2, (2) remove 'a_opensearch_utilities_' library, (3) added 'openpyxl', (4) Remove legacy client.count_tokens() call from Anthropic.

Issue #, if available:
Several issues raised during execution,

• Regions not matching available one when running workshop
• a_opensearch_utilities_ library no longer needed raising blocking run
• openpyxl library pending to be installed
• Anthropic legacy client.count_tokens() is no longer available
• Needed extra Sagemaker Role policies for OpenSearch Serverless policies and collection creation (done in workshop cdk)

Description of changes:

• Updated regions in notebook
• Removed a_opensearch_utilities_ library import
• Added openpyxl pip install at the begining
• Removed client.count_tokens() code
• Updated workshop CDK to include 2 extra needed aoss role policies

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