Spring-ai Fix IndexAlreadyExists exception for spring-ai-mongodb-atlas-store

In testing the docker mongodb/atlas container doesn't throw an exception when calling mongoTemplate.executeCommand({"createSearchIndexes": ...});. However, when using the Atlas service it does and throws a IndexAlreadyExists exception.

Added error handling for error code 68 or error code name IndexAlreadyExists. See: https://www.mongodb.com/docs/manual/reference/error-codes/

Fixes #910

Comment From: markpollack

Thanks! We are going to fix #698 as well, I wonder how you aren't blocked by that unless you are using that java module JVM option for opening classes to reflection.

Comment From: markpollack

merged in 24da2efc86bcce0bed951b7f8effe9fdf92270fb

Comment From: markpollack

@rozza the persistence issue is fixed now, let me know how it goes. see a1afb0db4644f216b3fead6142357fa468b7ca19