Simplify cluster installation process

[piotrmsc]

Description

Currently, in order to install kyma on a cluster you have to execute commands which basically replace placeholders in configuration yaml with empty string values. Additionally, you have a different command for k8s < 1.12.6 and > 1.12.6 for promtail. We should stick to the newer k8s versions.
Take a look for example here step 4.
To simplify this process, all placeholders can be moved to chart values as empty strings.
Our installation documentation should describe how to create a configmap with an override for example with own domain and TLS certificate instead of describing how to export variable and execute cat& sed commands.

Additionally, we can label installation CR with action install directly in the yaml file. This way no additional steps is required to trigger installation.

Reasons

Kyma should be easy to install without any sed&cat commands, just pure kubectly apply.

Attachments

[Tomasz-Smelcerz-SAP]

See also: kyma-project/test-infra#1024