ci: remove stale wolfi-presubmit package matrix entries (#2566)

What

Drop cadvisor, grafana-image-renderer, and mdbook from the
wolfi-presubmit matrix. Their YAMLs no longer exist in wolfi-dev/os
(both root-level lookups and full-repo code search return no matches),
so `wolfictl bump <pkg>` plus `make package/<pkg>` against the
wolfi-dev/os Makefile fails with "No rule to make target".

Why

These three matrix entries fail on every PR (including main) and
create persistent red CI noise that masks legitimate failures.
Removing them restores a green baseline without reducing coverage in
any meaningful way - the matrix still exercises 19 packages across
bubblewrap and qemu runners, covering cgroups, get/setcaps, diff
users, license-path, Perl/Python/Ruby builds, and more.

Notes

- Watch the next wolfi-presubmit run to confirm the matrix is green
  with these three removed.
- If anyone wants comparable coverage for cgroups (cadvisor was tagged
  "uses cgroups"), a replacement package from the still-existing
  matrix already exercises similar paths; if not, a follow-up could
  add a new entry from a currently-existing wolfi-dev/os YAML.

Signed-off-by: jmeridth <jmeridth@gmail.com>

Author: jmeridth

.github/workflows/wolfi-presubmit.yaml

@@ -78,15 +78,12 @@ jobs:
           #- glibc # takes ~35-40 minutes to build; not an all-encompassing signal of Melange functionality; TODO: replace with a smaller, related package
           #- xmlto # TODO: https://github.com/wolfi-dev/os/issues/26442
           - bubblewrap
-          - cadvisor # uses cgroups
           - dpkg
           - fixuid # uses a diff test user
           - fping # uses get/setcaps
           - gitsign
-          - grafana-image-renderer
           - guac
           - lzo
-          - mdbook
           - ncurses
           - perl-yaml-syck
           - postfix