Since git-lfs only supports http/https, git will need to authenticate over http/https when pushing files, even if you are using ssh/git protocol for git. Without the credential helper, you will be asked to enter your username and password for EVERY connection, which is pretty unusable.

https://github.com/github/git-lfs/wiki/Tutorial#credential-cachingstorage

 

Hence, it will be best that credential.helper is configured on Embedded Git as default settings on SourceTree.