fix: Refactor GetModifiedSettingsContent for PS5 compatibility

[ChrisBlankDe]

❔What, Why & How

This pull request makes a targeted improvement to the way the $schema property is handled in the GetModifiedSettingsContent function. The change ensures compatibility with PowerShell 5 by explicitly listing properties instead of using a wildcard, which could cause issues in that version.

• Improved PowerShell 5 compatibility by explicitly listing property names in Select-Object rather than using a wildcard, preventing the literal * property from being added when reordering $schema to the first position in the settings object.

Related to issue: #2285

✅ Checklist

• Add tests (E2E, unit tests)
• Update RELEASENOTES.md
• Update documentation (e.g. for new settings or scenarios)
• Add telemetry

[Copilot]

Pull request overview

This PR fixes a PowerShell 5 incompatibility in GetModifiedSettingsContent where reordering the $schema property via Select-Object ..., * -ExcludeProperty '$schema' could incorrectly introduce a literal "*": null entry in the resulting settings JSON. It updates the implementation to explicitly select properties in the desired order and documents the fix in the release notes.

Changes:

• Refactors $schema reordering in GetModifiedSettingsContent to avoid Select-Object * and be PowerShell 5-safe.
• Adds a release note entry referencing issue #2285 and the "*": null invalid JSON symptom.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
RELEASENOTES.md	Documents the fix for issue #2285 in the release notes.
Actions/CheckForUpdates/CheckForUpdates.HelperFunctions.ps1	Updates $schema property reordering logic to avoid PS5 adding a literal "*" property.