Setting auto assessment service to type: forking

[kjohn-msft]

Internal tracker: 24467908

Issue:
Systemd was reporting the assessment service as failed (even though it hadn't), because of the way the process hierarchy is set up.
This was showing up as:
"Active: failed (result: protocol)" in reporting.

Fix:
Change the type to forking to reflect shell script invoking py code.

[codecov]

Codecov Report

Merging #203 (07f7f24) into master (2e5c14b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #203   +/-   ##
=======================================
  Coverage   90.07%   90.07%           
=======================================
  Files          90       90           
  Lines       14423    14423           
=======================================
  Hits        12991    12991           
  Misses       1432     1432           

Flag	Coverage Δ
python27	90.07% <100.00%> (ø)
python39	90.07% <100.00%> (ø)

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Impacted Files	Coverage Δ
src/core/src/core_logic/ServiceManager.py	49.23% <100.00%> (ø)