Set platform from pr label (#1117)

Set platform from PR labels

* If PR specifies a ci-platform label, override the default test platform.
* PR tests can run in any supported platoform. Add the configuration required by libvirt to the environment.

(cherry picked from commit e7bf1b2)

ci/jenkins/pipelines/prs/skuba-test.Jenkinsfile

@@ -4,12 +4,16 @@
  *   - Basic skuba deployment, bootstrapping, and adding nodes to a cluster
  */
 
+
+// Platform for pr tests.
+def platform = 'vmware'
+
 // Branch specific repo
 def branch_repo = ""
 
 // Set the agent platform label. Cannot be set using the environment variables
 // because agent labels are evaluated before environment is set
-labels=''
+def labels=''
 node('caasp-team-private-integration') {
     stage('set-labels') {
         try {
@@ -25,6 +29,14 @@ node('caasp-team-private-integration') {
              def label = it.name.split(":")[1]
              labels = labels + " && " + label 
            }
+           // check if the PR request an specific test platform
+           def pr_platform_label = pr.labels.find {
+               it.name.startsWith("ci-platform")
+           }
+           if (pr_platform_label != null) {
+                platform = pr_platform_label.name.split(":")[1]
+           }
+
         } catch (Exception e) {
             echo "Error retrieving labels for PR ${e.getMessage()}"
             currentBuild.result = 'ABORTED'