SOS.Tests local CI execution is unsupported or exceeds leg timeout

## Build Information
Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1578741
Leg Name: Ubuntu_22_04_x64_Debug, Ubuntu_22_04_x64_Release, MacOS_Test_x64_Debug, MacOS_Test_x64_Release, Windows_Test_x86_Release, Alpine3_23_x64_Debug, Alpine3_23_x64_Release

## Error Message

```json
{
"ErrorPattern": "(?:The job running on agent .+ ran longer than the maximum time of 180 minutes|XUnit.*Tests failed: .*[\\\\/]SOS\\.Tests_net10\\.0_x86\\.html|XUnit.*Tests failed: .*[\\\\/]artifacts[\\\\/]log[\\\\/](?:Debug|Release)[\\\\/]SOS\\.Tests_net10\\.0_x64\\.log)",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

The new SOS.Tests harness runs a large host/runtime/flavor/dump/DAC matrix. Running the complete matrix in the existing local test legs causes three related temporary CI failures:

- Ubuntu and macOS test legs exceed the 180-minute job limit.
- Windows x86 loads the x64 `hostfxr.dll` (`0x800700C1`), followed by cascading EngineHost timeouts and test failures.
- Alpine attempts to execute the transferred glibc-targeted SOS.Tests apphost and reports `SOS.Tests: not found` on musl.

#5981 moves SOS.Tests to capture-family-sharded Helix work items, uses a shared platform payload, invokes `dotnet SOS.Tests.dll` on musl, and gates unsupported configurations. Until that integration lands, affected local SOS.Tests executions should be skipped without skipping the repository's existing non-SOS tests.

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1578741
**Error message validated:** `[(?:The job running on agent .+ ran longer than the maximum time of 180 minutes|XUnit.*Tests failed: .*[\\/]SOS\.Tests_net10\.0_x86\.html|XUnit.*Tests failed: .*[\\/]artifacts[\\/]log[\\/](?:Debug|Release)[\\/]SOS\.Tests_net10\.0_x64\.log)`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 9/2/2026 9:56:44 PM UTC

### Report
|Build|Repository|Step Name|Console log|Pull Request|
|---|---|---|---|---|
|[1591627](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591627)|dotnet/diagnostics|MacOS_arm64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1591627/logs/200)|dotnet/diagnostics#6024|
|[1589773](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1589773)|dotnet/diagnostics|Alpine3_23_x64_Debug|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1589773/logs/381)|dotnet/diagnostics#6018|
|[1583056](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1583056)|dotnet/diagnostics|Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1583056/logs/250)|dotnet/diagnostics#6001|
|[1583054](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1583054)|dotnet/diagnostics|Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1583054/logs/253)|dotnet/diagnostics#6000|
|[1583048](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1583048)|dotnet/diagnostics|Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1583048/logs/253)|dotnet/diagnostics#5999|
|[1582993](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1582993)|dotnet/diagnostics|Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1582993/logs/252)|dotnet/diagnostics#6008|
|[1582101](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1582101)|dotnet/diagnostics|MacOS_Test_x64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1582101/logs/336)||
|[1582214](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1582214)|dotnet/diagnostics|MacOS_Test_x64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1582214/logs/351)|dotnet/diagnostics#6008|
|[1581311](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1581311)|dotnet/diagnostics|MacOS_Test_x64_Debug|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1581311/logs/351)|dotnet/diagnostics#6005|
|[1580729](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1580729)|dotnet/diagnostics|MacOS_Test_x64_Debug|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1580729/logs/351)|dotnet/diagnostics#5999|
|[1580300](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1580300)|dotnet/diagnostics|MacOS_Test_x64_Debug|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1580300/logs/351)|dotnet/diagnostics#5980|
|[1580405](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1580405)|dotnet/diagnostics|MacOS_Test_x64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1580405/logs/264)||
|[1580102](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1580102)|dotnet/diagnostics|MacOS_Test_x64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1580102/logs/349)|dotnet/diagnostics#6004|
|[1580076](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1580076)|dotnet/diagnostics|MacOS_Test_x64_Debug|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1580076/logs/346)|dotnet/diagnostics#5993|
|[1579837](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1579837)|dotnet/diagnostics|MacOS_Test_x64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1579837/logs/351)|dotnet/diagnostics#5999|
|[1579739](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1579739)|dotnet/diagnostics|MacOS_Test_x64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1579739/logs/264)||
|[1578741](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1578741)|dotnet/diagnostics|MacOS_Test_x64_Release|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1578741/logs/351)|dotnet/diagnostics#5979|
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|0|2|17|

Start with the existing local test legs and the SOS.Tests harness behavior described here, then read issue #5981 for the planned sharding and platform handling. Done means affected local SOS.Tests executions are skipped without skipping the repository's existing non-SOS tests, while the timeout, Windows x86, and Alpine failures no longer occur.

Written by the indexing model from the issue text.