Remove some flaky tests that were just an overkill

[Gladwin Johnson VR (gladjohn)]

Fixes #5485

Changes proposed in this request
This pull request removes several integration tests related to device code flow scenarios from the DeviceCodeFlowIntegrationTest.cs file. The primary changes involve deleting tests for Arlington users, MSA users, and Azure AD Kerberos features, which streamlines the test suite in response to test failures.

Test removals:

• Removed Arlington device code flow tests, including both standard and ADFS user scenarios.
• Removed device code flow test for MSA users, which was previously marked as failing due to environment issues.

Kerberos feature test removal:

• Removed the entire Azure AD Kerberos device code flow test region, including the main test method and its supporting helper function.

Testing
tests

Performance impact
n/a

Documentation

• All relevant documentation is updated.

[Copilot]

Pull Request Overview

This pull request removes flaky and problematic integration tests from the device code flow test suite to improve test reliability. The changes streamline the test suite by eliminating tests that were causing failures or were deemed excessive.

• Removes Arlington-specific device code flow tests (both standard and ADFS user scenarios)
• Eliminates MSA (Microsoft Account) user device code flow test that was failing due to environment issues
• Completely removes the Azure AD Kerberos feature test region including the main test method and helper function