clone libbpf and make it easy to upgrade libbpf

Description

This PR removes the libbpf code that we have been copying and adds makefile infra to clone to a specific version.

Related issues/PRs

Todos

• [ ] Tests
• [ ] Documentation
• [ ] Release note

Release Note

TBD

Reminder for the reviewer

Make sure that this PR has the correct labels and milestone set.

Every PR needs one docs-* label.

• docs-pr-required: This change requires a change to the documentation that has not been completed yet.
• docs-completed: This change has all necessary documentation completed.
• docs-not-required: This change has no user-facing impact and requires no docs.

Every PR needs one release-note-* label.

• release-note-required: This PR has user-facing changes. Most PRs should have this label.
• release-note-not-required: This PR has no user-facing changes.

Other optional labels:

• cherry-pick-candidate: This PR should be cherry-picked to an earlier release. For bug fixes only.
• needs-operator-pr: This PR is related to install and requires a corresponding change to the operator.