Fix MySQL destructive test

* I7f50e32ced83af8f32fd7907cb5fc723055da121 separated pid directories for
  Pacemaker managed resources moving PID files to $HA_RSCTMP/$__SCRIPT_NAME
  This patch changes test to use name rather than PID
* Change pkill to to pkill -x to kill mysqld rathar than all processes
  that match mysqld pattern

Closes-Bug: 1399605
Related-Bug: 1388779
Change-Id: I34d540200f0ce2ff17b30e20a43f4d13c86b7492
Signed-off-by: Sergii Golovatiuk <sgolovatiuk@mirantis.com>