spec: Clean up Jenksinfile for JS test suite
spec: Clean up Jenksinfile for JS test suite

Test plan: Build still passes and runs all JS tests.

Change-Id: If5a379feaf0c67c59c83ab67d1db7b56ffdbf6c0
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/219113
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Tested-by: Jenkins
Reviewed-by: Rex Fleischer <360d56e185853f069087eaa5288d1374fc56d750@instructure.com>
QA-Review: Robert Lamb <bf934bf7cdbebe5899399a138c0cb75c4d783999@instructure.com>
Product-Review: Robert Lamb <bf934bf7cdbebe5899399a138c0cb75c4d783999@instructure.com>

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