Add focus for nightly jenkinsfile

Signed-off-by: Maciej Kwiek <maciej@isovalent.com>

Jenkinsfile.nightly

@@ -100,7 +100,7 @@ pipeline {
             steps {
                 parallel(
                     "Nightly":{
-                        sh 'cd ${TESTDIR}; ginkgo --focus="Nightly*" -v --failFast=${FAILFAST} -- -cilium.timeout=450m'
+                        sh 'cd ${TESTDIR}; ginkgo --focus="$(echo ${ghprbCommentBody} | sed -r "s/([^ ]* |^[^ ]*$)//" | sed "s/^$/Nightly*/")" -v --failFast=${FAILFAST} -- -cilium.timeout=450m'
                     },
                 )
             }