Replace the removed Mistral AI model aliases

Spring AI 2.0 removed the MistralAiApi.ChatModel constants LARGE, SMALL, MINISTRAL_3B_LATEST and MINISTRAL_8B_LATEST, which in Spring AI 1.x named the same models as MISTRAL_LARGE, MISTRAL_SMALL, MINISTRAL_3B and MINISTRAL_8B. This replaces them with those, so they use the model Spring AI 2.0 names for them, such as mistral-small-2603 for MISTRAL_SMALL. The constants of the models Spring AI 2.0 no longer lists, such as DEVSTRAL_SMALL or PIXTRAL, are left for review, as there is no constant for the same model.