jobs: gerrit, master, update-osmo-ci: fix build-discarder section

The build-discarder section was silently not working. It needs to be nested
below a 'properties' node.

Also the names need to be dashed and not camelCased.

Change-Id: I9503200a8873e616f9195d4bb1d6163c464b305e

jobs/gerrit-verifications.yml

@@ -187,11 +187,12 @@
     concurrent: '{obj:concurrent}'
     disabled: '{obj:disabled}'
     retry-count: 3 # scm checkout
-    build-discarder:
-      daysToKeep: 30
-      numToKeep: 120
-      artifactDaysToKeep: -1
-      artifactNumToKeep: -1
+    properties:
+      - build-discarder:
+          days-to-keep: 30
+          num-to-keep: 120
+          artifact-days-to-keep: -1
+          artifact-num-to-keep: -1
     description: |
       Pending gerrit code reviews of
       <a href="https://gerrit.osmocom.org/#/q/status:open+project:{repos}">{repos}</a>

jobs/master-builds.yml

@@ -271,11 +271,12 @@
     concurrent: '{obj:concurrent}'
     disabled: '{obj:disabled}'
     retry-count: 3 # scm checkout
-    build-discarder:
-      daysToKeep: 30
-      numToKeep: 120
-      artifactDaysToKeep: -1
-      artifactNumToKeep: -1
+    properties:
+      - build-discarder:
+          days-to-keep: 30
+          num-to-keep: 120
+          artifact-days-to-keep: -1
+          artifact-num-to-keep: -1
     description: |
       Automatic jenkins test job of
       <a href="http://git.osmocom.org/{repos}">{repos}</a>

jobs/update-osmo-ci-on-slaves.yml

@@ -6,9 +6,10 @@
           type: slave
           name: label
           values: [ OsmocomBuild1 , build1-debian9-lxc ]
-    build-discarder:
-      daysToKeep: 30
-      numToKeep: 120
+    properties:
+      - build-discarder:
+          days-to-keep: 30
+          num-to-keep: 120
     scm:
       - git:
           url: git://git.osmocom.org/osmo-ci