Drop workaround in process termination after IJPL-193111 is fixed

[ForNeVeR]

There's an issue IJPL-193111 that caused me to make a workaround (see the corresponding TODO):

handler.destroyProcess()
if (!handler.waitFor(100)) {
    // TODO[#524]: This is a workaround for https://youtrack.jetbrains.com/issue/IJPL-19311
    // handler.destroyProcess() won't destroy the process if LocalProcessService wasn't instantiated in this
    // IDE session.
    OSProcessUtil.killProcess(handler.process)
}
handler.waitFor()

Let's drop this after IJPL-19311 is fixed.