Update pr.yml to publish collections to production upon PR merge and handle staging collections

[botanical]

Context

In pr.yml, we currently have a no-op to publish collections to production. Update this step so that the collection is published to production when the PR is merged. Also, update so that the action is run on the staging directory

veda-data/.github/workflows/pr.yml

Lines 233 to 241 in 57f1005

	publish-to-prod-on-pr-merge:
	if: ${{ github.event_name == 'pull_request' && github.event.action == 'closed' && github.event.pull_request.merged == true }}
	runs-on: ubuntu-latest
	steps:
	- name: Checkout code
	uses: actions/checkout@v3
	- name: Publish to production on PR merge
	run: echo "NO-OP. This step runs when a PR is merged."

Acceptance Criteria

• action is updated to be triggered on the staging directory
• no-op step is removed and replaced with a step that publishes the collection to production when the PR is merged
• relevant testing is done to ensure step works correctly

[smohiudd]

blocked by NASA-IMPACT/veda-data-airflow#256