Keep job tasks when toggling free-form data collection

[rfontanarosa]

closes #2598

[gemini-code-assist]

Code Review

This pull request refactors the job strategy change handling in EditJobComponent to fetch the job directly from the draft survey service, introduces validation in DraftSurveyService to mark jobs with empty tasks as invalid, and adds unit tests for updateLoiTasks. The review feedback points out a potential bug where this.addLoiTaskId can leak across different jobs and suggests defensively guarding against undefined this.jobId instead of using non-null assertions.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 14.28571% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.10%. Comparing base (ff21f01) to head (69893f3).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
...ponents/edit-survey/edit-job/edit-job.component.ts	20.00%	4 Missing ⚠️
.../app/services/draft-survey/draft-survey.service.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2599      +/-   ##
==========================================
+ Coverage   62.94%   63.10%   +0.16%     
==========================================
  Files         121      121              
  Lines        3006     3011       +5     
  Branches      457      459       +2     
==========================================
+ Hits         1892     1900       +8     
+ Misses       1048     1046       -2     
+ Partials       66       65       -1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.