chore(ci): add skeleton for nightly E2E matrix workflow

[yachmenevas]

Description

Add a minimal skeleton for the nightly E2E matrix workflow. Preserves triggers, job order, and profile matrix; replaces logic with echo placeholders only.

Why do we need it, and what problem does it solve?

Validate triggers, dependencies, and matrix expansion without side effects before introducing real setup/tests/notifications.

What is the expected result?

Workflow runs on schedule/dispatch/PR, expands profiles matrix, and prints stage/profile messages only.

Checklist

• [ ] The code is covered by unit tests.
• [ ] e2e tests passed.
• [ ] Documentation updated according to the changes.
• [ ] Changes were tested in the Kubernetes cluster manually (workflow_dispatch).

Changelog entries

section: ci
type: chore
summary: "Add skeleton for nightly E2E matrix workflow with echo-only stages."