Enable SEMS Scotch TPL
Created by: bartlettroscoe
CC: @trilinos/framework, @ndellingwood
Description:
See #1400 and #2051 (closed) for motivation.
This only enables the Scotch TPL for CI build associated with the checkin-test-sems.sh script and post-push CI build linked to here. This does not enable the Scotch TPL for any other builds of Trilinos (including the PR testing that this PR is going to trigger).