Comment E2E tests out of LF build until ready

We'll be changing how the E2E tests are run on the TeamCity build
agents: instead of running the tests on the Linux build agent that's
building the site (which would use up processor resources on a Windows
build agent without TeamCity knowing that the Windows agent is occupied,
meaning TeamCity could try to start a different unrelated build on the
Windows agent, causing problems), we will instead run the E2E tests in a
separate TeamCity build task, after the Linux build agent has finished
its job. Until that's ready, we want to comment out the test-js-e2e
target so it won't take up five minutes of build time for no purpose.