add CI_REFSPEC parameter to various jobs

The patch adds CI_REFSPEC parameter to the following
jobs to enable testing a specific tf-a-ci-scripts refspec.

- tf-daily
- tf-main
- tf-ci-gateway
- tf-coverity
- tf-static-checks

The patch also renames SCRIPTS_REFSPEC and SCRIPTS_PROJECT
variables in the clone script.

Signed-off-by: Zelalem Aweke <zelalem.aweke@arm.com>
Change-Id: I0b7b78b8b7c0d1bb7df81a37769978f366e83da0
diff --git a/tf-main.yaml b/tf-main.yaml
index dced3e8..37eb4c0 100644
--- a/tf-main.yaml
+++ b/tf-main.yaml
@@ -35,6 +35,9 @@
             name: TFTF_GERRIT_REFSPEC
             default: '+refs/heads/master:refs/remotes/origin/master'
         - string:
+            name: CI_REFSPEC
+            default: '+refs/heads/master:refs/remotes/origin/master'
+        - string:
             name: SHARE_FOLDER
             default: '/srv/shared/${JOB_NAME}/${BUILD_NUMBER}'
             description: 'Folder containing shared repositories for downstream pipeline jobs'