Fix live service principal tests

[chlowell]

Need to update the principal's secret and certificate.

[joshfree]

@schaabs will lead a chat on our approach to live testing (cost vs benefit)

[joshfree]

Next step: @chlowell @christothes review tests offline to decide if which tests can be removed (low value which are redundant with existing tests) and circle back / share PR.

Live Certificate Test seems like one we want to keep.

@schaabs will take the action item to create the certificates for our tests to get them green again

[christothes]

I think we should be ok to keep the existing tests assuming we get the new testing subscription for this. It should be as simple as updating the pipeline environment secrets, once they are available.