Deprecate certmanager.install in favor of installCertmanager

What does this MR do?

Deprecate certmanager.install in favor of installCertmanager

Deprecate certmanager.install to allow upgrading to a new certmanager version in a later release. Newer certmager charts enforce schema validation and do not allow additional properties.

certmanager.install takes precedence over installCertmanager until it is removed to not break any existing configurations.

Relates #5928 (closed)

Changelog: changed

Related issues

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