Test flakiness for Microsoft.NET.Sdk.StaticWebAssets.Tests.StaticWebAssetsIntegrationTest.Build_DoesNotUpdateManifest_WhenHasNotChanged

## Build Information
Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1529489
Build error leg or test failing: Build_DoesNotUpdateManifest_WhenHasNotChanged (FullFramework: windows (x64) run on windows.amd64.vs2026.pre.scout.open)
Pull request: https://github.com/dotnet/sdk/pull/55493

## Error Message

Exception Message
```
Test method Microsoft.NET.Sdk.StaticWebAssets.Tests.StaticWebAssetsIntegrationTest.Build_DoesNotUpdateManifest_WhenHasNotChanged threw exception:
FluentAssertions.Execution.AssertionFailedException: Expected string to be the same string, but they differ at index 21:
↓ (actual)
"…1,"Hash":"suG2pZRiRV…"
"…1,"Hash":"YaJCboCN5L…"
↑ (expected).
```

CallStack
```
at FluentAssertions.Execution.FallbackTestFramework.Throw(String message)
at FluentAssertions.Execution.DefaultAssertionStrategy.HandleFailure(String message)
at FluentAssertions.Execution.AssertionChain.FailWith(Func`1 getFailureReason)
at FluentAssertions.Execution.AssertionChain.FailWith(String message)
at FluentAssertions.Primitives.StringEqualityStrategy.ValidateAgainstMismatch(AssertionChain assertionChain, String subject, String expected)
at FluentAssertions.Primitives.StringAssertions`1.Be(String expected, String because, Object[] becauseArgs)
at Microsoft.NET.Sdk.StaticWebAssets.Tests.StaticWebAssetsIntegrationTest.Build_DoesNotUpdateManifest_WhenHasNotChanged() in /_/test/Microsoft.NET.Sdk.StaticWebAssets.Tests/StaticWebAssetsIntegrationTest.cs:line 121
at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
```

The test asserts that rebuilding without changes leaves the generated static web assets manifest byte-for-byte identical, but the `Hash` value of an asset differs between the two builds. The mismatched hash values vary from run to run, so the JSON below matches on the test name rather than on the hash contents.

**DO NOT USE JSON BELOW IF THIS IS A BUILD BREAK** otherwise build analysis will allow pull requests to merge that break the build worse. For a build break, do not use this issue form. Make a regular new issue.

Fill the error message using [step by step known issues guidance](https://github.com/dotnet/arcade/blob/main/Documentation/Build%20Analysis/KnownIssueJsonStepByStep.md).

```json
{
"ErrorMessage": "StaticWebAssetsIntegrationTest.Build_DoesNotUpdateManifest_WhenHasNotChanged threw exception",
"ErrorPattern": "",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1529489
**Error message validated:** `[StaticWebAssetsIntegrationTest.Build_DoesNotUpdateManifest_WhenHasNotChanged threw exception`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 7/29/2026 8:31:46 AM UTC

### Report

|Build|Repository|Test|Pull Request|
|---|---|---|---|
|[1577776](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1577776)|dotnet/sdk|[Microsoft.NET.Sdk.StaticWebAssets.Tests.StaticWebAssetsContentFingerprintingIntegrationTest.Publish_OverrideHtmlAssetPlaceholders](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1577776&view=ms.vss-test-web.build-test-results-tab&runId=43504230&resultId=113855)|dotnet/sdk#56086|
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|0|0|1|