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

[SouadHadjiat]

Proposed changes

• filter observables created from indicators (API & playbook)
• Adding unit tests

This solution to not create observables in this case has been seen with product team.

Related issues

• network-traffic Observable created from a malicious-activity indicator doesn't have any dst_ref and linked object #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]

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 ⚠️
...-graphql/src/modules/indicator/indicator-domain.ts	50.00%	1 Missing ⚠️
...raphql/src/modules/playbook/playbook-components.ts	50.00%	1 Missing ⚠️

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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