GitHub Action: Avoid "if: always()"

[Jonathan Champ]

From https://docs.github.com/en/actions/learn-github-actions/expressions#always

If you want to run a job or step regardless of its success or failure, use the recommended alternative: if: ${{ !cancelled() }}

In ncstate-delta/moodle-mod_zoom#531, I proposed change to our plugin's GitHub Action. It occurred to me that some of these changes might be beneficial to include in the example file gha.dist.yml. Here are some of the benefits it may offer:

1. Only run moodle-plugin-ci steps when the moodle-plugin-ci installs successfully
2. Use !cancelled() instead of always() as recommended by GitHub
3. If the job has been cancelled, mark the job as failed so that PR status checks cannot be bypassed

If you would prefer, I would be willing to open a PR. Mainly, I want to make sure I'm only suggesting desired/acceptable changes.

[Ruslan Kabalin]

Hello @jrchamp, thanks, your proposal sounds good. I am not sure if sucessful installation of moodle-plugin-ci needs to be checked though, if it fails with non-zero exit status, it is supposed to stop at that installation step.

[Jonathan Champ]

Thanks @kabalin! With both always() and !cancelled(), the steps do continue (because failure() is true). However, that may not be a problem, as each of the steps will also fail with a non-zero exit status. I'll create a PR with part 1 removed for review.