[Flaky Test] Quarantine 2 flaky tests (#14503)

Quarantines 2 intermittently failing tests detected across multiple
independent CI sources.

---

## `NuGetStaticGraphRestore_InheritsCoordinatorGrant_DoesNotDeadlock`

**Flaky-test key** (automated de-duplication — do not edit):
```text
flaky-test-id: Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.NuGetStaticGraphRestore_InheritsCoordinatorGrant_DoesNotDeadlock
```

**Action:** Quarantine (6a)
Tracked by #14488

- **Distinct sources:** 5 (2 PRs + 3 rolling builds)
- **PRs:** #14371, #14401
- **Rolling builds:**
[1511941](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1511941),
[1517682](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1517682),
[1519967](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1519967)
- **Legs/TFMs:** CoreOnMac, FullOnWindows, FullOnWindows Release /
net10.0, net472
- **Assembly:** MSBuild.Coordinator.UnitTests
- **Window:** 2026-07-15 – 2026-07-21
- **Sample error:** `System.TimeoutException : Test failed due to
timeout: process is active for more than 60 sec.`

---

## `TaskExceptionHandlingTest`

**Flaky-test key** (automated de-duplication — do not edit):
```text
flaky-test-id: Microsoft.Build.UnitTests.BackEnd.TaskExecutionHost_Tests.TaskExceptionHandlingTest
```

**Action:** Quarantine (6a)
Tracked by #14459

- **Distinct sources:** 5 (1 PR + 4 rolling builds)
- **PRs:** #14315
- **Rolling builds:**
[1510684](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1510684),
[1517216](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1517216),
[1519472](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1519472),
[1519928](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1519928)
- **Legs/TFMs:** FullOnWindows Release / net472
- **Assembly:** Microsoft.Build.Engine.UnitTests
- **Window:** 2026-07-15 – 2026-07-21
- **Sample error:** `Shouldly.ShouldAssertException` in
`TaskExceptionHandlingTest`




> [!WARNING]
> <details>
> <summary>Firewall blocked 2 domains</summary>
>
> The following domains were blocked by the firewall during workflow
execution:
>
> - `awmgmcpg`
> - `southcentralus0.in.applicationinsights.azure.com`
>> To allow these domains, add them to the `network.allowed` list in
your workflow frontmatter:
>
> ```yaml
> network:
>   allowed:
>     - defaults
>     - "awmgmcpg"
>     - "southcentralus0.in.applicationinsights.azure.com"
> ```
>
> See [Network
Configuration](https://github.github.com/gh-aw/reference/network/) for
more information.
>
> </details>


> Generated by [Flaky Test
Triage](https://github.com/dotnet/msbuild/actions/runs/30006270630) ·
126 AIC · ⌖ 6.2 AIC · ⊞ 14.8K ·
[◷](https://github.com/search?q=repo%3Adotnet%2Fmsbuild+%22gh-aw-workflow-id%3A+flaky-test-detector.agent%22&type=pullrequests)

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

src/Build.UnitTests/BackEnd/TaskExecutionHost_Tests.cs

@@ -1752,6 +1752,7 @@ public void TestTaskDictionaryOutputItems()
             ml.AssertLogContains("a=b");
         }
 
+        [ActiveIssue("https://github.com/dotnet/msbuild/issues/14459")]
         [Theory]
         [InlineData(typeof(OutOfMemoryException), true)]
         [InlineData(typeof(ArgumentException), false)]

src/MSBuild.Coordinator.UnitTests/CoordinatorIntegration_Tests.cs

@@ -129,6 +129,7 @@ public async Task NestedBuild_InheritsCoordinatorGrant_DoesNotDeadlock()
         buildOutput.ShouldNotContain("Failed to connect to the build coordinator");
     }
 
+    [ActiveIssue("https://github.com/dotnet/msbuild/issues/14488")]
     [Fact]
     public async Task NuGetStaticGraphRestore_InheritsCoordinatorGrant_DoesNotDeadlock()
     {