Change CSOT exception hierarchy

[vbabanin]

MongoTimeoutException is stable public API documented as "waiting for a server or connection to become available," implying the operation was not executed. MongoOperationTimeoutException does not provide that guarantee: the operation may have been sent to the server and may have executed. Keeping it as a subclass of MongoTimeoutException is therefore semantically incorrect and may mislead consumers that catch MongoTimeoutException into assuming no operation was executed.

Changes:

• Make MongoOperationTimeoutException extend MongoClientException instead of MongoTimeoutException to avoid breaking the semantic guarantee that MongoTimeoutException implies the operation was not executed
• Handle MongoOperationTimeoutException explicitly in instanceof MongoTimeoutException checks to preserve existing behavior for transaction labeling, connection pool events, and logging

Options considered:

• extends MongoClientException (what is proposed in this PR) - sibling to MongoTimeoutException. Both are client-side failures, no shared timeout semantics.
• extends MongoException - too broad. MongoException is the root for everything including server errors. MongoOperationTimeoutException is a client-side concern.
• New intermediate class like MongoOperationException - adds a class just for one subclass. Unnecessary abstraction.
• extends RuntimeException directly - breaks out of the MongoException hierarchy entirely. Users catching MongoException would miss it.

JAVA-5438

[Copilot]

Pull request overview

This PR updates the Java driver’s timeout exception semantics by removing the inheritance relationship between MongoOperationTimeoutException and MongoTimeoutException, so that catching MongoTimeoutException continues to imply “timed out waiting for a server/connection” (i.e., the operation was not executed).

Changes:

• Changed MongoOperationTimeoutException to extend MongoClientException instead of MongoTimeoutException.
• Updated transaction error labeling and commit labeling logic to treat MongoOperationTimeoutException as a timeout-equivalent case.
• Updated connection pool/server selection timeout handling and structured logging logic to explicitly account for MongoOperationTimeoutException.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
driver-sync/src/main/com/mongodb/client/internal/MongoClusterImpl.java	Adds MongoOperationTimeoutException handling when applying transient transaction error labels.
driver-reactive-streams/src/main/com/mongodb/reactivestreams/client/internal/OperationExecutorImpl.java	Adds MongoOperationTimeoutException handling when applying transient transaction error labels in reactive execution.
driver-core/src/main/com/mongodb/MongoOperationTimeoutException.java	Changes the exception superclass to MongoClientException to avoid implying “not executed” semantics.
driver-core/src/main/com/mongodb/internal/operation/CommitTransactionOperation.java	Treats MongoOperationTimeoutException as eligible for UnknownTransactionCommitResult labeling decisions.
driver-core/src/main/com/mongodb/internal/connection/LoadBalancedCluster.java	Broadens timeout-exception factory return type and ensures timeoutMS produces MongoOperationTimeoutException.
driver-core/src/main/com/mongodb/internal/connection/DefaultConnectionPool.java	Ensures connection checkout failure classification/maintenance handling treats MongoOperationTimeoutException as a timeout.
driver-core/src/main/com/mongodb/internal/connection/BaseCluster.java	Ensures server selection timeout creation/logging properly accounts for MongoOperationTimeoutException.

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