.NET: Increase credential timeout for Integration Tests

[westey-m]

Motivation and Context

Integration tests are often failing with a timeout on new AzureCliCredential().

Description

• Increasing the timeout to 60s from 13s to avoid these.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

Updates .NET integration tests to use a shared Azure CLI credential helper with a longer process timeout, reducing CI flakiness from AzureCliCredential initialization.

Changes:

• Add Shared.IntegrationTests.TestCredentials helper that creates an AzureCliCredential with a 60s ProcessTimeout.
• Wire the helper into several integration test projects and update call sites to use it.
• Extend MSBuild shared-code injection (Shared.props) and solution items to include the new shared helper.

Reviewed changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests.csproj	Enables injection of the shared Azure credentials helper into this test project.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Framework/IntegrationTest.cs	Switches workflow test harness to use TestCredentials.CreateAzureCliCredential().
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/AzureAgentProviderTest.cs	Uses shared credential helper for provider construction.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Agents/VisionAgentProvider.cs	Uses shared credential helper for AIProjectClient.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Agents/TestAgentProvider.cs	Uses shared credential helper for AIProjectClient.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Agents/PoemAgentProvider.cs	Uses shared credential helper for AIProjectClient.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Agents/MathChatAgentProvider.cs	Uses shared credential helper for AIProjectClient.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Agents/MarketingAgentProvider.cs	Uses shared credential helper for AIProjectClient.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Agents/FunctionToolAgentProvider.cs	Uses shared credential helper for AIProjectClient.
dotnet/tests/Microsoft.Agents.AI.FoundryMemory.IntegrationTests/Microsoft.Agents.AI.FoundryMemory.IntegrationTests.csproj	Enables injection of the shared Azure credentials helper into this test project.
dotnet/tests/Microsoft.Agents.AI.FoundryMemory.IntegrationTests/FoundryMemoryProviderTests.cs	Uses shared credential helper for AIProjectClient.
dotnet/tests/Microsoft.Agents.AI.DurableTask.IntegrationTests/TestHelper.cs	Uses shared credential helper for AzureOpenAIClient when authenticating via Azure CLI.
dotnet/tests/Microsoft.Agents.AI.DurableTask.IntegrationTests/Microsoft.Agents.AI.DurableTask.IntegrationTests.csproj	Enables injection of the shared Azure credentials helper into this test project.
dotnet/tests/AzureAIAgentsPersistent.IntegrationTests/AzureAIAgentsPersistentFixture.cs	Uses shared credential helper for PersistentAgentsClient.
dotnet/tests/AzureAIAgentsPersistent.IntegrationTests/AzureAIAgentsPersistent.IntegrationTests.csproj	Enables injection of the shared Azure credentials helper into this test project.
dotnet/tests/AzureAI.IntegrationTests/AzureAI.IntegrationTests.csproj	Enables injection of the shared Azure credentials helper into this test project.
dotnet/tests/AzureAI.IntegrationTests/AIProjectClientFixture.cs	Uses shared credential helper for AIProjectClient.
dotnet/src/Shared/IntegrationTestsAzureCredentials/TestCredentials.cs	Introduces shared helper creating AzureCliCredential with longer process timeout.
dotnet/src/Shared/IntegrationTestsAzureCredentials/README.md	Documents how to enable the shared credentials helper via MSBuild property.
dotnet/eng/MSBuild/Shared.props	Adds a new conditional Compile include to inject the shared credentials helper.
dotnet/agent-framework-dotnet.slnx	Adds solution items for the new shared credentials helper folder/files.