CHEF-29389: Update Azure SDK gems to v2 variants

[balasubramanian-s]

Description

This pull request upgrades the Azure Ruby SDK dependencies across the codebase from the legacy Azure SDK gems (e.g., azure_mgmt_resources, azure_graph_rbac, azure_mgmt_key_vault) to their newer *2 variants (e.g., azure_mgmt_resources2).

The upgrade is required because the legacy Azure Ruby SDK gems are incompatible with Faraday v2. The *2 gems are maintained in the Chef fork of the Azure SDK:
https://github.com/chef/azure-sdk-for-ruby

Dependency and SDK upgrade:

• Updated Azure SDK dependencies in train.gemspec to use the *2 gems:

azure_graph_rbac2
azure_mgmt_key_vault2
azure_mgmt_resources2

• Removed all legacy unused Azure SDK gem dependencies.
• Updated all require statements and SDK references throughout the codebase to use the new modules and clients (e.g., Azure::Resources2::Profiles::Latest::Mgmt::Client, MsRestAzure2, MsRest2)

Test updates:

• Modified all Azure-related test code in test/unit/transports/azure_test.rb to use the new *2 classes and modules, ensuring tests remain valid with the SDK upgrade.

Related Issue

CHEF-28233: Update Azure SDK gems to v2 variants

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New content (non-breaking change)
• Breaking change (a content change which would break existing functionality or processes)

Checklist:

• I have read the CONTRIBUTING document.
• All tests pass locally with my changes.
• I have added tests that prove my fix is effective or that my feature works.
• Code follows the project's style guidelines.