Update pr.yml to use sm2a dag run for publication

[anayeaye]

What

Update automated publish action(s) to use SM2A DAGRun endpoints instead of the legacy workflows dataset/publish endpoint. May require adjustments for auth and will definitely require a slight adjustment to the body posted to the dag run endpoint--for example see this s3 event bridge lambda that submits a request for vector discovery.

AC

• publish-new-datasets job in pr.yml uses sm2a endpoints