Python: Remove MotorCommandCursor in import typing (#5222)

### Motivation and Context
#4433 
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### Description
* If `tornado` is not installed, importing `MotorCommandCursor` will
fail due to the conditional import requirement. The fix is to import its
parent class `AgnosticCommandCursor`

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### Contribution Checklist

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- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

python/semantic_kernel/connectors/memory/mongodb_atlas/mongodb_atlas_memory_store.py

@@ -5,7 +5,7 @@
 from importlib import metadata
 from typing import Any, List, Mapping, Optional, Tuple
 
-from motor import MotorCommandCursor, core, motor_asyncio
+from motor import core, motor_asyncio
 from numpy import ndarray
 from pymongo import DeleteOne, ReadPreference, UpdateOne, results
 from pymongo.driver_info import DriverInfo
@@ -272,7 +272,7 @@ async def get_nearest_matches(
         if min_relevance_score is not None:
             pipeline.append({"$match": {"score": {"$gte": min_relevance_score}}})
 
-        cursor: MotorCommandCursor = self.database[collection_name].aggregate(pipeline)
+        cursor = self.database[collection_name].aggregate(pipeline)
 
         return [
             (