Drop repo_ref from jenkins.properties

It's propagated downstream by the '-main' build flows already

Author: adriaanm

scripts/jobs/integrate/bootstrap

@@ -317,8 +317,6 @@ scalaVerToBinary() {
 determineScalaVersion() {
   cd $WORKSPACE
   parseScalaProperties "versions.properties"
-  echo "repo_ref=2.12.x" >> $baseDir/jenkins.properties # for the -dist downstream jobs that build the actual archives
-
 
   # each of the branches below defines the following vars: SCALA_VER_BASE, SCALA_VER_SUFFIX, SCALADOC_SOURCE_LINKS_VER, publishToSonatype
   if [ -z "$SCALA_VER_BASE" ]; then