Set GERRIT_REFSPEC to empty line

For some unknown reason gerrit-plugin logic requires empty line for
pulling remote master branch

PROD-36426

Change-Id: I16faea5b6dd2d673ad1d8c07a17f72a52ccb3691
diff --git a/jobs/templates/self-deploy-jobs.yaml b/jobs/templates/self-deploy-jobs.yaml
index fb31b57..8ec2f91 100644
--- a/jobs/templates/self-deploy-jobs.yaml
+++ b/jobs/templates/self-deploy-jobs.yaml
@@ -7,8 +7,8 @@
     name: self-deploy-jobs
     parameters:
     - string:
-        default: 'refs/for/master'
-        description: 'tcp-qa review refspec'
+        default: ''
+        description: 'tcp-qa review refspec; leave empty for master'
         name: GERRIT_REFSPEC
         trim: 'true'
     - bool: