Fix lint issues, CI build (envtest), and e2e MinIO image for release-1.15

[kaovilai]

Summary

• Bump golangci-lint to v1.64.6 and update .golangci.yaml config
• Fix all lint issues: use-any (interface{} → any), var-declaration, unnecessary-stmt, testifylint, gosimple, staticcheck, errcheck, gosec
• Fix CI build: replace broken go.kubebuilder.io GCS tarball download with setup-envtest in hack/build-image/Dockerfile
• Fix e2e tests: replace deleted bitnami/minio:2021.6.17-debian-10-r7 image with building from current Bitnami Dockerfile (matching main branch approach), cached across e2e jobs
• Fix codespell typo (colume → volume)

Does your change fix a particular issue?

Fixes CI build and e2e test infrastructure failures on release-1.15.

Follow up from #8757 with lint fixes.

Please indicate you've done the following:

• Accepted the DCO.
• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main.