New review comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/29780#discussion_r704354391

Comment:
1. Removal of the EFI files should happen in the `post-remove` hook, not the `post-install` hook.
2. If you're going to run `rm -f`, there's no need to test for existing with `if [ -f ... ]`.