Remove your ZSH completion in favor of the completion script distributed and maintained by ZSH

Hello,

Today I wanted to use some cool features of the ZSH tab completion function that ZSH provides[1]. Only after half an hour of trying to debug why something didn't work for me, I noticed that I'm not even loading ZSH's git tab completion, but I'm loading the implementation distributed by Git, which is undoubtedly inferior in terms of features.

ZSH completion is almost always distributed with every distribution of ZSH, so there is no need for the two projects to maintain two completion functions for the same program :).

[1]: https://github.com/zsh-users/zsh/blob/zsh-5.9/Completion/Unix/Command/_git

Doron.