enh: disable cert-manager by default

[mglotov]

Prerequisites

Please answer the following questions for yourself before submitting an issue. YOU MAY DELETE THE PREREQUISITES SECTION.

• I am running the latest version
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed

Expected Behavior

Cert-manager is installed only if it's needed

Current Behavior

Cert-manager is installed by default

[mglotov]

Has been done here #176