Updated the Bedrock rag template (#12462)

Updates the bedrock rag template.
- Removes pinecone and replaces with FAISS as the vector store
- Fixes the environment variables, setting defaults
- Adds a `main.py` test file quick sanity testing
- Updates README.md with correct instructions

templates/rag-aws-bedrock/main.py

@@ -0,0 +1,6 @@
+from rag_aws_bedrock.chain import chain
+
+if __name__ == "__main__":
+    query = "What is this data about?"
+
+    print(chain.invoke(query))