[benchmark] refactor killing of providers in run performance script
[benchmark] refactor killing of providers in run performance script

* only kill if provider has been started before
* use pkill only in case where maven is used

Change-Id: I0080395fe26bd2630b8ba5f836883229cbb460a8

clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr