test(NODE-7147): Revert field presence changes from server 8.2.0

[tadjik1]

Description

Summary of Changes

Updated spec tests for change stream. All affected files pass tests, failures unrelated (even though they are also about change streams).

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

Updates the unified change stream spec tests to reflect that updateDescription.disambiguatedPaths should not be present unless showExpandedEvents is enabled, while explicitly excluding the server behavior regression in MongoDB 8.2.0.

Changes:

• Add a unified spec test asserting disambiguatedPaths is absent when showExpandedEvents is false/unset, skipping server 8.2.0 via version gating.
• Adjust runOnRequirements topologies in the YAML spec test file to match the updated coverage set.
• Keep YAML and JSON variants of the unified spec test in sync.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
test/spec/change-streams/unified/change-streams-disambiguatedPaths.yml	Adds version-gated test ensuring disambiguatedPaths absence without showExpandedEvents; adjusts topologies list.
test/spec/change-streams/unified/change-streams-disambiguatedPaths.json	JSON equivalent of the added test and requirements to keep unified spec coverage aligned.