Development: Fix E2E tests condition to run single-node for PRs

[egekocabas]

Checklist

General

• I chose a title conforming to the naming conventions for pull requests.

Motivation and Context

Previously, all E2E tests were running as multi-node due to incorrect if conditions in the workflow. The conditions were incorrectly checking github.event.workflow_run.pull_requests, causing the single-node test case to never run.

This PR fixes the logic by correctly checking github.event.workflow_run.event == 'pull_request' to determine if the triggering workflow was caused by a PR. Now:

• Tests will run on Single-node artemis if the workflow_run event was triggered by a PR.
• Tests will run on Multi-node artemis if the workflow_run event was triggered by other events (e.g., push to develop, main, release branches, or release).

Description

• if condition in test-e2e.yml fixed.