PYTHON-6012 - Consolidate TopologySettings into a single shared class

[NoahStapp]

PYTHON-6012

Changes in this PR

Refactored ToplogySettings to use a shared generic base class, leaving only Pool and Monitor type info to differ between async and sync.

Test Plan

Existing test suite.

Checklist

Checklist for Author

• Did you update the changelog (if necessary)?
• Is there test coverage?
• Is any followup work tracked in a JIRA ticket? If so, add link(s).

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Is all relevant documentation (README or docstring) updated?

[Copilot]

Pull request overview

This PR refactors the driver’s TopologySettings implementation to reduce duplication between synchronous and asynchronous clients by extracting shared behavior into a new shared base class, and updates affected tests to import TOPOLOGY_TYPE from its canonical module.

Changes:

• Introduce pymongo/settings_shared.py with _BaseTopologySettings containing the shared TopologySettings logic.
• Update sync/async TopologySettings to inherit from the shared base and delegate initialization.
• Update sync/async client tests to import TOPOLOGY_TYPE from pymongo.topology_description instead of the settings modules.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/test_client.py	Update import source for TOPOLOGY_TYPE to match refactor.
test/asynchronous/test_client.py	Update import source for TOPOLOGY_TYPE to match refactor.
pymongo/synchronous/settings.py	Convert TopologySettings to a thin subclass of the shared base.
pymongo/asynchronous/settings.py	Convert TopologySettings to a thin subclass of the shared base.
pymongo/settings_shared.py	New shared base class factoring out common TopologySettings behavior.

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[aclark4life]

LGTM

[codecov]

Codecov Report

❌ Patch coverage is 99.09091% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pymongo/settings_shared.py	98.95%	1 Missing ⚠️

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