TOOLS-2598 changes the behavior of the tools so that if there is a PEM file with multiple certificates, the first certificate is the one that's compared against the private key in the file, rather than the last certificate.

We wanted to add an integration test alongside those changes, but in order to have the test work on Evergreen, we would've needed to setup a mongod / replica set using different options just for this one test. This proved to be more work than it's worth, so I manually verified that the TOOLS-2598 changes work as intended.

We can add the integration test (see attached) as part of this ticket once we're using mlaunch (TOOLS-3226) to make it easier to set up a replica set with those different options. This ticket should take a few mins to complete after that.