fix: job hook scripts pre-emptively expands shell parameters

[harryfinbow]

The job_started_script and job_completed_script pre-emptively expand any shell parameters defined in them, resulting in them being expanded when the /opt/runner/job_started_script.sh and /opt/runner/job_completed_script.sh files are created and not at runtime of the job.

Instructing the heredoc document to skip expanding any shell parameters gives the expected functionality without having to escape them in the config file.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.68%. Comparing base (e9a7d28) to head (0947e6c).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #686   +/-   ##
=======================================
  Coverage   86.68%   86.68%           
=======================================
  Files          35       35           
  Lines        1510     1510           
=======================================
  Hits         1309     1309           
  Misses        201      201           

Flag	Coverage Δ
api	63.90% <ø> (ø)
unit	68.41% <ø> (ø)

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