[Issue #5555] Improve speed of terminating geoserver

[mtnorthcott]

PR to stop geoserver using psutil instead of os.kill and sleeping as termination typically takes <30 seconds.

Checklist

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[codecov]

Codecov Report

Merging #5539 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5539   +/-   ##
=======================================
  Coverage   57.56%   57.56%           
=======================================
  Files         171      171           
  Lines       19526    19526           
  Branches     3196     3196           
=======================================
  Hits        11241    11241           
  Misses       7277     7277           
  Partials     1008     1008

[afabiani]

@mtnorthcott let's please attach a ticket to this PR. Thanks.