Fix PowerShell unit tests

[flanakin]

🛠️ Description

Fix mocking issue with unit tests

📋 Checklist

🔬 How did you test this change?

• 🤏 Lint tests
• 🤞 PS -WhatIf / az validate
• 👍 Manually deployed + verified
• 💪 Unit tests
• 🙌 Integration tests

🙋‍♀️ Do any of the following that apply?

• 🚨 This is a breaking change.
• 🤏 The change is less than 20 lines of code.

📑 Did you update docs/changelog.md?

• ✅ Updated changelog (required for dev PRs)
• ➡️ Will add log in a future PR (feature branch PRs only)
• ❎ Log not needed (small/internal change)

📖 Did you update documentation?

• ✅ Public docs in docs (required for dev)
• ✅ Public docs in docs-mslearn (required for dev)
• ✅ Internal dev docs in docs-wiki (required for dev)
• ✅ Internal dev docs in src (required for dev)
• ➡️ Will add docs in a future PR (feature branch PRs only)
• ❎ Docs not needed (small/internal change)

[Copilot]

Pull request overview

This PR fixes PowerShell unit test mocking issues that were causing test failures. The changes ensure test assertions properly match the production code behavior and that all necessary functions are mocked correctly.

Changes:

• Updated New-FinOpsCostExport unit tests to apply .Trim('/') in assertions to match production code behavior
• Added parameter declarations to the New-AzResourceGroupDeployment stub function to enable proper parameter validation in tests
• Added missing mock for Initialize-FinOpsHubDeployment in the Deploy-FinOpsHub 'Old tests' context

Reviewed changes

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

File	Description
src/powershell/Tests/Unit/New-FinOpsCostExport.Tests.ps1	Updated test assertions to include .Trim('/') to match the rootFolderPath trimming behavior in the production code
src/powershell/Tests/Unit/Deploy-FinOpsHub.Tests.ps1	Added parameter declarations to stub function and added missing Initialize-FinOpsHubDeployment mock to prevent test failures