Adapt automated E2E pre-release tests to check already released version of Eclipse Che

[dmytro-ndp]

Is your task related to a problem? Please describe.

There is a plan to make release omitting release candidate.
It requires adapting automated E2E tests to check already released version instead of release candidate in pre-release testing jobs on ci.centos and on CRW CCI:

• test che-server, che-keycloak and che-postgres images of release tag, instead of rc tag;
• use chectl:latest/operator: instead of chectl:next/operator:nightly;
• run tests against Eclipse Che with TLS enabled, in order to reflect fixup of Eclipse Che pod bootstrap timeout on chectl install, when using Che operator with TLS and unsigned certificate on non-OpenShift kube #16280 issue.