Update FinOps docs to remove TCO Calculator references and replace with Azure Migrate guidance

[Copilot]

This PR addresses the deprecation of the Azure TCO Calculator by removing references to it in the FinOps documentation and updating the guidance to use Azure Migrate for cost estimation during migration planning.

Changes Made

1. Planning and estimating page (docs-mslearn/framework/quantify/planning.md)

Before:

- If you're migrating on-premises infrastructure to the cloud:
  - Use the [Total Cost of Ownership (TCO) Calculator](https://azure.microsoft.com/pricing/tco/calculator) to get a high-level comparison of on-premises vs. cloud servers, databases, storage, and networking infrastructure.
    > After entering details of your on-premises infrastructure, the TCO Calculator presents cost reports showcasing the cost differences between running workloads on-premises compared to Azure that can be saved and shared across team members.
  - Use [Azure Migrate](https://azure.microsoft.com/products/azure-migrate) to automate the discovering and migration of your on-premises workloads.

After:

- If you're migrating on-premises infrastructure to the cloud:
  - Use [Azure Migrate](https://azure.microsoft.com/products/azure-migrate) to automate the discovering and migration of your on-premises workloads and get an estimate comparison of on-premises vs. Azure costs.

2. FinOps tools and services page (docs-mslearn/framework/manage/tools-services.md)

Before:

- **TCO Calculator**: Allows you to estimate the cost savings achievable by migrating your application workloads to Microsoft Cloud.  
- **Azure Migrate**: Discover, migrate, and modernize on-premises infrastructure.

After:

- **Azure Migrate**: Discover, migrate, and modernize on-premises infrastructure. Estimate the cost savings achievable by migrating your application to Microsoft Cloud.

Summary

• ✅ Removed all references to the deprecated TCO Calculator
• ✅ Updated Azure Migrate descriptions to include cost estimation functionality
• ✅ Aligned with new guidance to use Azure Migrate business case feature for migration cost analysis
• ✅ Maintained existing documentation structure and formatting

The changes ensure users are directed to the appropriate tools for migration cost estimation while the TCO Calculator transitions to retirement.

Fixes #1728.

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[Vahe Minasyan (vaheminasyan2)]

Arthur Clares (@arthurclares) / Michael Flanakin (@flanakin) / Anthony Romano (@aromano2) / CaddyG - can one of you please review and this PR? Thank you.

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[Vahe Minasyan (vaheminasyan2)]

HI Arthur Clares (@arthurclares) , I see you approved these changes and merged to the branch, but the pages don't reflect the changes. Can you please check? Thanks.

[Vahe Minasyan (vaheminasyan2)]

Hi Arthur Clares (@arthurclares), can you please help to push this update live? The page isn't updated yet, so wanted to see if you can help. Thank you.

[Vahe Minasyan (vaheminasyan2)]

Hi Anthony Romano (@aromano2) Arthur Clares (@arthurclares) Michael Flanakin (@flanakin) CaddyG these two pages are still mentioning the TCO calculator. It looks like changes merged in this PR haven't been implemented yet. Can you please help to get it implemented? Thank you.