👷 Launch runs for regression tests from CI (2/2)

Related to

Related to #1904 by @amygutierrez

Part of a series toward automating regression testing

https://github.com/cmi-dair/slurm_testing/pull/1
1999 + this PR

Description

Once https://github.com/cmi-dair/slurm_testing/pull/1 is merged, these changes will allow this repo to trigger remote testing runs

on pushes with "[run reg-suite]" in the commit message
on pull requests to develop when the PRs are
- opened
- marked ready-for-review
- reopened

Technical details

This is just part of the solution to #1904. With these changes, we
1. run the updated code on downsampled code on a HPC
2. report back success or failure of each run to a GitHub check
Subsequent PRs to FCP-INDI/C-PAC + cmi-dair/slurm_testing + FCP-INDI/regtest-runlogs + amygutierrez/regression_dashboard will automate correlating the new run to a previous run (for the regression test) and reporting back those results

Tests

I've been running all these changes in CI configuration on my forks of these repos to test.

Screenshots

When runs fail, the checks should show red like https://github.com/FCP-INDI/C-PAC/assets/5974438/c2613976-a1d7-4237-a8c1-2015fe1d674c

In any case, logs should be available on GitHub like this.

Checklist

[x] My pull request has a descriptive title (not a vague title like Update index.md).
[x] My pull request targets the develop branch of the repository.
[x] My commit messages follow best practices.
[x] My code follows the established code style of the repository.
[ ] I added tests for the changes I made (if applicable).
[ ] I updated the changelog.
[x] I added or updated documentation (if applicable).
[x] I tried running the project locally and verified that there are no visible errors.

Developer Certificate of Origin

``` Developer Certificate of Origin Version 1.1 Copyright (C) 2004, 2006 The Linux Foundation and its contributors. 1 Letterman Drive Suite D4700 San Francisco, CA, 94129 Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Developer's Certificate of Origin 1.1 By making a contribution to this project, I certify that: (a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or (b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or (c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it. (d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved. ```

FCP-INDI / C-PAC