change Model for template rag or other services

[ALutz273]

💡 Feature Description

I would like to change the model from the “rag” template. For example, from ibm-granite/granite-3.3-8b-instruct to ibm-granite-4.1-8b or Mistral-Small-3.2-24B-Instruct-2506

################
#### list models ###
################
#-> ai-services application  model list -t rag-cpu  --runtime podman
Models in application template rag-cpu:
- BAAI/bge-reranker-v2-m3 (1)
- ibm-granite/granite-embedding-278m-multilingual (2)
- ibm-granite/granite-3.3-8b-instruct (3)

####################
#### change models ####
####################
ai-services application  model change -m 3 "ibm-granite/granite-4.1-8b" -t rag-cpu  --runtime podman 

❗ Why This Matters

This can make the service faster or better, depending on the use case.

🧩 Requirements

Changes to the ai-services CLI.
Changes defaults of templates.