Replace `workflow-context` action with GitHub's `job` context

[joverlee521]

Our workflow-context action was added because GitHub did not have access to a reusable workflow's context

.github/actions/workflow-context/action.yaml

Lines 10 to 21 in faab911

	This is necessary since GitHub currently does not support accessing the
	reusable workflow's context within itself using a GitHub context variable.
	According to the GitHub Action docs²:
	When a reusable workflow is triggered by a caller workflow, the github
	context is always associated with the caller workflow.
	There are existing issues requesting this feature, so we can replace this
	action when they get resolved:
	- https://github.com/actions/toolkit/issues/1264
	- https://github.com/actions/runner/issues/2417

GitHub has just resolved the upstream issue (actions/runner#2417 (comment)), so we can replace the custom action with the built-in job context.