fix(connectors-sdk): BaseSettings serialization and security issues (#7100)

[Powlinett]

Proposed changes

• Use SecretStr type for OPENCTI_TOKEN env var to avoid leaking credentials in logs
• Use field_serializer for CONNECTOR_SCOPE for consistency
• Fix serialization issue by making deprecated fields optional (allow model_dump() with exclude_none)
• Extract _SettingsLoader into its own dedicated module
• Update downstream connector tests after OPENCTI_TOKEN type change

Related issues

• Close fix(connectors-sdk): BaseSettings serialization and security issues #7100

Checklist

• I consider the submitted work as finished
• I have signed my commits using GPG key.
• I tested the code for its functionality using different use cases
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

This PR is part of a split from #6559. The logger module work continues in a stacked PR based on this branch.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #7101       +/-   ##
===========================================
+ Coverage   35.64%   66.60%   +30.96%     
===========================================
  Files        2048     1308      -740     
  Lines      125310    70265    -55045     
===========================================
+ Hits        44672    46803     +2131     
+ Misses      80638    23462    -57176     

Files with missing lines	Coverage Δ
...rs-sdk/connectors_sdk/settings/_settings_loader.py	100.00% <100.00%> (ø)
...ors-sdk/connectors_sdk/settings/annotated_types.py	100.00% <ø> (ø)
...ctors-sdk/connectors_sdk/settings/base_settings.py	100.00% <100.00%> (ø)

... and 1199 files with indirect coverage changes

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[Copilot]

Pull request overview

This PR addresses serialization and secret-handling issues in connectors-sdk settings models by switching OPENCTI_TOKEN to SecretStr, normalizing CONNECTOR_SCOPE JSON serialization via field_serializer, making deprecated fields optional for safer dumping, and extracting _SettingsLoader into a dedicated module. It also updates downstream connector tests to reflect the new SecretStr behavior.

Changes:

• Update BaseSettings/BaseConnectorSettings to treat OPENCTI_TOKEN as SecretStr and selectively reveal it only for pycti helper config output.
• Standardize CONNECTOR_SCOPE serialization for pycti via field_serializer, and refactor _SettingsLoader into connectors_sdk.settings._settings_loader.
• Update SDK and connector test suites/fixtures to align with new token typing and updated scope/log-level fixture values.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
stream/microsoft-sentinel-intel/tests/microsoft_sentinel_intel/test_config.py	Adjust expected OpenCTI token representation in dumped config.
internal-enrichment/qualys-cve-enrichment/tests/test_connector/test_settings.py	Update token assertions for SecretStr.
internal-enrichment/polyswarm-sandbox/tests/test_connector.py	Update token assertions for SecretStr.
internal-enrichment/censys-enrichment/tests/censys_enrichment/test_config.py	Update token assertions for SecretStr.
external-import/flare/tests/test_connector/test_settings.py	Ensure helper config contains clear token via get_secret_value().
external-import/ctm360-hackerview-feed/tests/test_connector/test_settings.py	Update token assertions for SecretStr.
external-import/ctm360-cyna-feed/tests/test_connector/test_settings.py	Update token assertions for SecretStr.
external-import/ctm360-cyberblindspot-feed/tests/test_connector/test_settings.py	Update token assertions for SecretStr.
connectors-sdk/tests/test_settings/test_settings_loader.py	Add dedicated tests for new _SettingsLoader module behavior.
connectors-sdk/tests/test_settings/test_deprecation_migration.py	Update scope fixtures to match comma-separated behavior.
connectors-sdk/tests/test_settings/test_base_settings.py	Update base settings tests for SecretStr token + scope serialization changes.
connectors-sdk/tests/test_settings/test_annotated_types.py	Remove tests tied to ListFromString JSON serialization behavior that was moved.
connectors-sdk/tests/test_settings/data/config.test.yml	Update config fixture scope/log-level values.
connectors-sdk/tests/test_settings/data/.env.test	Update env fixture scope/log-level values.
connectors-sdk/tests/test_settings/conftest.py	Point fixtures to _settings_loader module + update scope fixture.
connectors-sdk/connectors_sdk/settings/base_settings.py	Implement SecretStr token, per-field serialization rules, deprecated-field optionality, and improved deprecated namespace handling.
connectors-sdk/connectors_sdk/settings/annotated_types.py	Remove ListFromString JSON serializer now that scope serialization is handled in settings models.
connectors-sdk/connectors_sdk/settings/_settings_loader.py	Extract _SettingsLoader into a dedicated module.