Crossgen runtime runs are completely failing

Currently, all crossgen runs in the [dotnet-runtime-perf](https://dev.azure.com/dnceng/internal/_build?definitionId=702) pipeline are failing. One such failure being seen is the following:

```
(.venv) \w\B2DF099F\e>python \w\B2DF099F\e\performance\src\scenarios\crossgen2\pre.py crossgen2 --core-root \p\Core_Root --single System.Net.WebProxy.dll
----------------------------------------------
Initializing logger 2025-04-08 04:23:43.559211
----------------------------------------------
$ pushd "\p\Core_Root"
$ \p\Core_Root\corerun.exe \p\Core_Root\crossgen2\crossgen2.dll \p\Core_Root\System.Net.WebProxy.dll -o \w\B2DF099F\e\crossgen.out\System.Net.WebProxy.ni.dll -O -r \p\Core_Root\System.*.dll -r \p\Core_Root\Microsoft.*.dll -r \p\Core_Root\netstandard.dll -r \p\Core_Root\mscorlib.dll
Activation Context creation failed. Error: 0x00000002
Unhandled exception. System.IO.FileNotFoundException: Could not load file or assembly '\p\Core_Root\crossgen2\crossgen2.dll'. The system cannot find the file specified.
File name: '\p\Core_Root\crossgen2\crossgen2.dll'
$ popd
Process exited with status 3762504530
```