PYTHON-6029 Consolidate non-IO code in Pool and Connection into shared base class

[NoahStapp]

PYTHON-6029

Changes in this PR

See ticket.

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?

[codecov]

Codecov Report

❌ Patch coverage is 96.58120% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pymongo/pool_shared.py	96.15%	2 Missing and 6 partials ⚠️

📢 Thoughts on this report? Let us know!

[NoahStapp]

I've removed the unused client parameter to avoid additional type complexity with the consolidation, but it does mean this PR has changes across usages. I could see instead moving that removal to a follow-up PR, but that leaves the codebase in an intermediate state where we have known dead code in-between.

[Copilot]

🟢 Approval recommended

Static review identified no blocking regressions in the extraction or updated callers; tests were not run.

0 open findings

What changed in this PR

Consolidates shared, non-I/O pool and connection logic to reduce duplication between PyMongo’s synchronous and asynchronous drivers.

Changes:

• Extracts common state and methods into generic base classes.
• Removes the unused client argument from apply_timeout and updates callers.
• Moves the telemetry protocol import under TYPE_CHECKING.

File	Description
pymongo/​synchronous/​pool.py	Uses shared base classes.
pymongo/​synchronous/​command_runner.py	Updates timeout call.
pymongo/​synchronous/​client_bulk.py	Updates client bulk timeout call.
pymongo/​synchronous/​bulk.py	Updates collection bulk timeout call.
pymongo/​pool_shared.py	Adds common pool and connection implementations.
pymongo/​message.py	Updates shared calls and removes obsolete type ignores.
pymongo/​asynchronous/​pool.py	Uses shared base classes.
pymongo/​asynchronous/​command_runner.py	Updates timeout call.
pymongo/​asynchronous/​client_bulk.py	Updates client bulk timeout call.
pymongo/​asynchronous/​bulk.py	Updates collection bulk timeout call.
pymongo/​_telemetry.py	Makes protocol import type-checking-only.

🧠 Review effort: Balanced

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[aclark4life]

Probably fine to remove unused client parameter, LGTM