SignTool not producing log files

During signing the build will output the following text:

```

SignToolTask starting. |  
-- | --
| DryRun: False |  
| Signing mode: Real |  
| MicroBuild signing logs will be in (Signing*.binlog): E:\A\_work\1968\s\artifacts\log\Release\ |  
| MicroBuild signing configuration will be in (Round*.proj): E:\A\_work\1968\s\artifacts\tmp\Release\ |  
```

In reality though no Signing.binlog is generated to that directory. Our official builds upload that entire directory as a Build Artifact and Signing.binlog is not included.

Example build: https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=2927998&view=artifacts