[internal] Shift left testing

[umbertoDifa]

Problem

1. We must avoid being notified of a failure late after the code is merged.
2. We must avoid being notified about an e2e failure only after the nightly run
3. If multiple PRs are merged to master only the last one runs the full GHA

Solution

1. Run unit tests for each PR (Ideally we'd run e2e but curretly it takes 45min so not worth it)
2. Run e2e for each merge to master
3. Remove concurrency so that each commit to master gets its own full run. This is important cause in case of multiple PRs we can quickly identify which commit is responsible of a failure (otherwise we wouldn't know what introduced a failure and we'd need to revert them all)

[Copilot]

Pull Request Overview

This PR aims to improve early defect detection by shifting testing left in the development process. It introduces unit tests on pull requests and incorporates e2e tests during merges to master.

• Added a pull_request trigger with branch filters in JOB_tests.yml to run unit tests on PRs.
• Updated EVENT_merge_to_master.yml to add an e2e_tests job and include it as a dependency for notification jobs.
• Adjusted Slack notification message formatting for consistency.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/workflows/JOB_tests.yml	Added pull_request trigger with branch filters to run tests for PRs.
.github/workflows/EVENT_merge_to_master.yml	Introduced e2e_tests job and updated dependency arrays for warn_on_fail and success notifications.