Update CommitmentDiscountUsage transform to use parse_resourceid

[flanakin]

🛠️ Description

Update CommitmentDiscountUsage_transform_v1_0() to use parse_resourceid()

📋 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)
• ✅ 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 reviewed 2 out of 2 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

src/templates/finops-hub/modules/scripts/IngestionSetup.kql:1248

• Ensure that the new behavior introduced by parse_resourceid is covered by unit or integration tests.

| extend tmp_ResourceDetails = parse_resourceid(ResourceId)