CI: Fix missing script block in jenkinsfiles

Change-Id: Ib4b6e4887695f230ea7a5b0c879b29fc5a13be4f
(cherry picked from commit d60f23ecbd)
(cherry picked from commit ce8a23fdf9)
(cherry picked from commit f0d1ce50af)

tests/CI/unittests.jenkinsfile

@@ -183,8 +183,10 @@ pipeline {
 	}
 	post {
 		cleanup {
-			if (env.CLEANUP_WS_UNITTESTS.toBoolean()) {
-				cleanWs deleteDirs: true, notFailBuild: false
+			script {
+				if (env.CLEANUP_WS_UNITTESTS.toBoolean()) {
+					cleanWs deleteDirs: true, notFailBuild: false
+				}
 			}
 		}
 		/*