[backend] Filter observables creation with refs from indicators (#5293)

[SouadHadjiat]

Proposed changes

• filter observables created from indicators
• Adding unit tests
• TODO: need to test and validate this solution (to be sure we want to stop creating these observables)

Related issues

• #5293

Checklist

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

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 73.68421% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 67.69%. Comparing base (5993973) to head (99c1111).

Files	Patch %	Lines
...encti-platform/opencti-graphql/src/utils/syntax.js	80.00%	3 Missing :warning:
...-graphql/src/modules/indicator/indicator-domain.ts	50.00%	1 Missing :warning:
...raphql/src/modules/playbook/playbook-components.ts	50.00%	1 Missing :warning:

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6163   +/-   ##
=======================================
  Coverage   67.69%   67.69%           
=======================================
  Files         532      532           
  Lines       65010    65025   +15     
  Branches     5445     5449    +4     
=======================================
+ Hits        44009    44021   +12     
- Misses      21001    21004    +3     

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