A recent change in Helm 3.20.1 broke our usage of pluck. Helm 4 is not
impacted.

We can workaround this by explictly checking for nil values instead of
using pluck until this is fixed upstream:
  https://github.com/helm/helm/issues/31971

Relates gitlab-org/charts/gitlab#6366

Changelog: fixed

Fix certmanager annotation regression in Helm 3.20.1 [9.8 Backport]

See merge request !4929

Merged-by: João Alexandre Cunha <j.a.cunha@gmail.com>
Approved-by: João Alexandre Cunha <j.a.cunha@gmail.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>
Co-authored-by: Clemens Beck <cbeck@gitlab.com>

[ci skip]

[ci skip]