(JJB): Ability to simulate a nightly running test date manually

Change-Id: Ic0439580b5db9ca96c5fe48f429957e07de7ef21
diff --git a/jjb/OnosSystemTest/onos-test-pipeline.yaml b/jjb/OnosSystemTest/onos-test-pipeline.yaml
index 0ab997f..c697abf 100644
--- a/jjb/OnosSystemTest/onos-test-pipeline.yaml
+++ b/jjb/OnosSystemTest/onos-test-pipeline.yaml
@@ -149,6 +149,11 @@
          description: "ONOS and TestON versions to run on. Multiple branches supported."
 
       - string:
+         name: simulate_day
+         default: ""
+         description: 'Enter a day prefix (first 3 letters of a day, lowercase) to simulate running a nightly test on that day. Leave this field empty to default to today. Example: type "sun" for Sunday'
+
+      - string:
          name: ONOSJAVAOPTS
          default: "\"${{JAVA_OPTS:--Xms8G -Xmx8G -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -Dkaraf.log.console=INFO -Dds.lock.timeout.milliseconds=60000}}\""
          description: 'ONOS cell JAVA_OPTS setting.'