Burn_in_tests should pick up changed files in mongo-enterprise-modules files

Currently, burn_in_tests picks up changed files in the mongodb/mongo repo. It should do the same for the 10gen/mongo-enterprise-modules repo.

User story:
As a MongoDB engineer, I should be able to run burn_in_tests patch builds that run the jstests I've changed in the 10gen/mongo-enterprise-modules repo, ensuring that my jstests changes do not cause them to fail.

AC:

• Burn_in_tests picks up changes to jstests in 10gen/mongo-enterprise-modules repo