CLOUDP-295785 - move away from GHA variables

[MaciejKaras]

Summary

GitHub Variables cannot be accessed from forks. Forks are used by engineers to create PRs in this repo, but due to previously mentioned limitation some GitHub Actions fail.

This PR moves the variables from GitHub to root-context file. Additionally to make contexts work in GitHub Actions I had to create gha-private-context file similar to evg-private-context, otherwise the switch command would fail.

After this change all GitHub variables can be removed.

Proof of Work

Passing evg CI and GitHub Checks.

Checklist

• Have you linked a jira ticket and/or is the ticket in the title?
• Have you checked whether your jira ticket required DOCSP changes?
• Have you added changelog file?
  • use skip-changelog label if not needed
  • refer to Changelog files and Release Notes section in CONTRIBUTING.md for more details

[github-actions]

⚠️ (this preview might not be accurate if the PR is not rebased on current master branch)

MCK 1.3.0 Release Notes

New Features

Multi-Architecture Support

We've added comprehensive multi-architecture support for the kubernetes operator. This enhancement enables deployment on IBM Power (ppc64le) and IBM Z (s390x) architectures alongside
existing x86_64 support. Core images (operator, agent, init containers, database, readiness probe) now support multiple architectures. We do not add support IBM and ARM support for Ops-Manager and the init-ops-manager image.

• MongoDB Agent images have been migrated to new container repository: quay.io/mongodb/mongodb-agent.
  • the agents in the new repository will support the x86-64, ARM64, s390x, and ppc64le architectures. More can be read in the public docs.
  • operator running >=MCK1.3.0 and static cannot use the agent images from the old container repository quay.io/mongodb/mongodb-agent-ubi.
• quay.io/mongodb/mongodb-agent-ubi should not be used anymore, it's only there for backwards compatibility.

Bug Fixes

• This change fixes the current complex and difficult-to-maintain architecture for stateful set containers, which relies on an "agent matrix" to map operator and agent versions which led to a sheer amount of images.
• We solve this by shifting to a 3-container setup. This new design eliminates the need for the operator-version/agent-version matrix by adding one additional container containing all required binaries. This architecture maps to what we already do with the mongodb-database container.
• Fixed an issue where the readiness probe reported the node as ready even when its authentication mechanism was not in sync with the other nodes, potentially causing premature restarts.

Other Changes

• Optional permissions for PersistentVolumeClaim moved to a separate role. When managing the operator with Helm it is possible to disable permissions for PersistentVolumeClaim resources by setting operator.enablePVCResize value to false (true by default). When enabled, previously these permissions were part of the primary operator role. With this change, permissions have a separate role.
• subresourceEnabled Helm value was removed. This setting used to be true by default and made it possible to exclude subresource permissions from the operator role by specifying false as the value. We are removing this configuration option, making the operator roles always have subresource permissions. This setting was introduced as a temporary solution for this OpenShift issue. The issue has since been resolved and the setting is no longer needed.
• We have deliberately not published the container images for OpsManager versions 7.0.16, 8.0.8, 8.0.9 and 8.0.10 due to a bug in the OpsManager which prevents MCK customers to upgrade their OpsManager deployments to those versions.