[backend] Upsert indicator: skip decay computation if no score change (#15476)

[lndrtrbn]

Proposed changes

• During Indicator upsert, do not re-compute decay properties if no score changes

Related issues

• Closes Playbook action overrides decay exclusion rule #15476

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case (coverage and e2e)
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

When a Playbook sends a bundle that contains decayed Indicators, the function addIndicator is called with as input an object with for value of x_opencti_score the current decayed score of the indicator. This decayed score is used to compute the valid_until date but the computation awaits the base score, not a decayed one, so the result date is invalid.

This behavior cannot be resolved directly in the addIndicator function as we have no idea at this point if it is a creation or an upsert. So the fix is done directly in the upsert codebase, there are already some specific conditions to skip decay computation on upsert, the fix adds a new one when the live score does not changed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.53%. Comparing base (c622aab) to head (e98682d).
⚠️ Report is 19 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #15525   +/-   ##
=======================================
  Coverage   33.52%   33.53%           
=======================================
  Files        3167     3167           
  Lines      214711   214732   +21     
  Branches    39437    39438    +1     
=======================================
+ Hits        71990    72011   +21     
  Misses     142721   142721           

Flag	Coverage Δ
opencti-client-python	45.60% <ø> (ø)
opencti-front	2.94% <ø> (ø)
opencti-graphql	69.81% <100.00%> (+<0.01%)	⬆️

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