Add Hercules-EMC to the Jenkins configurable parameter list (#2685)

This quick-fix PR is to update the Jenkins Pipeline's configurable
parameter list to include the **Hercules-EMC** node.
This allows Jenkins users to restart Jobs in the controller when no
updates have been made.

ci/Jenkinsfile

@@ -76,7 +76,7 @@ pipeline {
                     Machine = machine[0].toUpperCase() + machine.substring(1)
                     echo "Getting Common Workspace for ${Machine}"
                     ws("${custom_workspace[machine]}/${env.CHANGE_ID}") {
-                        properties([parameters([[$class: 'NodeParameterDefinition', allowedSlaves: ['built-in', 'Hera-EMC', 'Orion-EMC'], defaultSlaves: ['built-in'], name: '', nodeEligibility: [$class: 'AllNodeEligibility'], triggerIfResult: 'allCases']])])
+                        properties([parameters([[$class: 'NodeParameterDefinition', allowedSlaves: ['built-in', 'Hercules-EMC' 'Hera-EMC', 'Orion-EMC'], defaultSlaves: ['built-in'], name: '', nodeEligibility: [$class: 'AllNodeEligibility'], triggerIfResult: 'allCases']])])
                         HOME = "${WORKSPACE}"
                         sh(script: "mkdir -p ${HOME}/RUNTESTS;rm -Rf ${HOME}/RUNTESTS/*")
                         sh(script: """${GH} pr edit ${env.CHANGE_ID} --repo ${repo_url} --add-label "CI-${Machine}-Building" --remove-label "CI-${Machine}-Ready" """)