test(NODE-7462): add spec tests for disaggregated storage

[tadjik1]

Description

Summary of Changes

Add server discovery and monitoring tests for replica sets that use a constant setVersion value instead of incrementing it on reconfig.

Notes for Reviewers

What is the motivation for this change?

Spec PR
NODE-7462 | DRIVERS-3397

Release Highlight

Release notes highlight

Double check the following

• Lint is passing (npm run check:lint)
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[Copilot]

Pull request overview

Adds new SDAM replica set spec test fixtures to validate driver behavior when setVersion is constant (disaggregated storage) and during migrations between incrementing and constant setVersion behaviors.

Changes:

• Add SDAM test for disaggregated storage where primary staleness detection relies on electionId when setVersion is unchanged.
• Add SDAM migration tests covering ASC→DSC (using setVersionASC + 1) and DSC→ASC (force reconfig with high setVersion).
• Add SDAM test ensuring host/member list updates are applied even when setVersion and electionId do not change.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/spec/server-discovery-and-monitoring/rs/migration_to_disaggregated_storage.yml	YAML fixture describing ASC→DSC forward migration behavior.
test/spec/server-discovery-and-monitoring/rs/migration_to_disaggregated_storage.json	Executed SDAM spec test for ASC→DSC migration scenario.
test/spec/server-discovery-and-monitoring/rs/migration_from_disaggregated_storage.yml	YAML fixture describing DSC→ASC reverse migration behavior.
test/spec/server-discovery-and-monitoring/rs/migration_from_disaggregated_storage.json	Executed SDAM spec test for DSC→ASC migration scenario.
test/spec/server-discovery-and-monitoring/rs/member_list_update_with_unchanged_setversion_and_electionid.yml	YAML fixture for member list changes without setVersion/electionId changes.
test/spec/server-discovery-and-monitoring/rs/member_list_update_with_unchanged_setversion_and_electionid.json	Executed SDAM spec test ensuring host list updates are still applied.
test/spec/server-discovery-and-monitoring/rs/disaggregated_storage_setversion.yml	YAML fixture for constant setVersion + changing electionId behavior.
test/spec/server-discovery-and-monitoring/rs/disaggregated_storage_setversion.json	Executed SDAM spec test validating staleness logic with constant setVersion.

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