- By default, use only `ingressClassName` for ingress class name and
corresponding field in cert-manager
- Only use old 'kubernetes.io/ingress.class' if
ingress.useOldClassAnnotation is set
- Allow for using old annotation only for backwards compatibility, eg.
for GCP
- Closes#2267 and #1570
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Co-authored-by: Ilya Kreymer <ikreymer@gmail.com>