[ci-scan] Build break: runtime-diagnostics MSBuild MSB1001 Unknown switch (--verbosity:m)

## Build Information
Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1591981
Build error leg or test failing: cDAC_verify_windows_x64_release / DAC_windows_x64_release / cDAC_windows_x64_release / windows-x86 release CdacStressTest - Build / Test (runtime-diagnostics, def 309)

KBE authoring guidance (ci-failure-scan)

- `Error Details` is for readers. Paste the full exception, stack trace, or build error excerpt so the failure is understandable without opening the raw log.
- Build Analysis parses only the single JSON block under `Error Message`.
- `ErrorMessage` is a case-sensitive ordinal `String.Contains` substring copied verbatim from the failing log.
- Set `BuildRetry` to `true` only for a clear infrastructure retry case. `ExcludeConsoleLog` disables Helix console-log scanning.

## Error Details

The `Build / Test` step in the runtime-diagnostics pipeline invokes MSBuild with `--verbosity:m` (double-dash) alongside `--property:*` switches, which MSBuild rejects. The build fails before any tests run, so every DAC/cDAC leg of the pipeline breaks. This reproduces on 100% of scanned builds (source 1591981 and following build 1593890, plus 1590309 and 1588392), so the failure is stable and persistent across the entire scanned window; true origin may predate 2026-09-08.

```
MSBUILD : error MSB1001: Unknown switch.
Full command line: '\.dotnet\sdk\10.0.111\MSBuild.dll -maxcpucount --verbosity:m -tlp:default=auto --property:ContinuousIntegrationBuild=True ... --verbosity:minimal /m /nologo /clp:Summary /nr:False /warnaserror \.packages\microsoft.dotnet.arcade.sdk\...\tools\Build.proj ...'
Switches appended by response files:
Switch: -build

For switch syntax, type "MSBuild -help"
Build failed with exit code 1. Check errors above.
```

## Error Message

```json
{
"ErrorMessage": [
"MSBUILD : error MSB1001: Unknown switch.",
"--verbosity:m -tlp:default=auto"
],
"ErrorPattern": "",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

Agentic workflow metadata (ci-failure-scan)

Workflow artifact: ci-failure-scan
Artifact kind: kbe-verification
Verified match count: 1 hits in failure.log

---
Filed by [`ci-failure-scan`](https://github.com/dotnet/runtime/blob/main/.github/workflows/ci-failure-scan.md) (detection only). [`ci-failure-fix`](https://github.com/dotnet/runtime/blob/main/.github/workflows/ci-failure-fix.md) walks open `[ci-scan]` KBEs and either opens a small fix PR or comments here to loop in owners — it never disables the test.

> [!NOTE]
> This issue was generated by an AI agent (GitHub Copilot / ci-failure-scan workflow).

> Generated by [CI Outer-Loop Failure Scanner](https://github.com/dotnet/runtime/actions/runs/34729903269) · opus48 · 996.9 AIC · ⌖ 16.7 AIC · ⊞ 19.7K · [◷](https://github.com/search?q=repo%3Adotnet%2Fruntime+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Fruntime%2Fci-failure-scan%22&type=issues)

### Report
|Build|Repository|Step Name|Console log|Pull Request|
|---|---|---|---|---|
|[1595722](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1595722)|dotnet/runtime|Build / Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1595722/logs/384)|dotnet/runtime#133878|
|[1595271](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1595271)|dotnet/runtime|Build / Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1595271/logs/397)|dotnet/runtime#133850|
|[1594914](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594914)|dotnet/runtime|Build / Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1594914/logs/407)||
|[1594508](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594508)|dotnet/runtime|Build / Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1594508/logs/392)|dotnet/runtime#130050|
|[1594483](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1594483)|dotnet/runtime|Build / Test|[Log](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_apis/build/builds/1594483/logs/449)||
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|2|5|5|

Start with the runtime-diagnostics pipeline's Build / Test step and the MSBuild command shown in the failure from build 1591981. Reproduce the failing DAC/cDAC build and trace where the --verbosity:m and --property switches are assembled; done means the build accepts the arguments and reaches the tests.

Written by the indexing model from the issue text.