Replace cancel-workflow-action with concurrency

[BrianJKoopman]

Description

This removes the styfle/cancel-workflow-action reusable action with the native concurrency feature of workflows.

Motivation and Context

Fixes #356.

This is just the first example in https://github.com/styfle/cancel-workflow-action, which should be the same behavior we're getting out of the reusable action right now.

How Has This Been Tested?

This has not been tested. I might just push some extra commit to this branch to see the workflow cancel here.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Repository management (change unrelated to the main code base)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[BrianJKoopman]

Test push was a success, first runs cancelled! https://github.com/simonsobs/ocs/actions/runs/24090053172