[client] remove hardcoded first value in list method when using getAll

[axelfahy]

Currently, when listing entities with the getAll parameter, the first value is overwritten. This PR removes the overwrite of the first value when using getAll in list methods, for all entities.

Proposed changes

• Remove the hardcoding of the first value when using getAll in list methods for all entities.

Related issues

• first parameter is not customizable when using the getAll option in list method #457 (comment)

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

Further comments

PR #796 did not fix this related issue.

FYI, the following entities did not use getAll and it the variable has been removed:

• pycti/entities/opencti_kill_chain_phase.py
• pycti/entities/opencti_location.py
• pycti/entities/opencti_marking_definition.py
• pycti/entities/opencti_observed_data.py
• pycti/entities/opencti_stix_nested_ref_relationship.py
• pycti/entities/opencti_threat_actor.py
• pycti/entities/opencti_threat_actor_group.py
• pycti/entities/opencti_threat_actor_individual.py