Speed up generation

[lucacome]

Proposed changes

Problem: Generation is slow and throws a bunch of warnings.

Solution: Use go:generate once per package as suggested in https://github.com/maxbrunsfeld/counterfeiter#step-2b---add-counterfeitergenerate-directives

Testing: I removed all the generated files and they are re-generated correctly.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

NONE

[salonichf5]

lgtm