RemoteExecutor Swallows Errors and Throws Invalid Exceptions

- [x] This issue is blocking
- [x] This issue is causing unreasonable pain

I could be holding it wrong but it does not seem to be working as expected.

Microsoft.DotNet.RemoteExecutor Version 6.0.0-beta.20508.3 (_Are there non beta version available?_)

Installed via https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json

The following method runs without any assertation exceptions. I would expect it to fail.

``` c#
RemoteExecutor.Invoke(() =>
{
Assert.True(false);
}).Dispose();
```

The following code throws an exception. I would expect none.
``` c#
RemoteExecutor.Invoke(() =>
{
return RemoteExecutor.SuccessExitCode;
}).Dispose();
```
Message:
Exit code was -2147450749 but it should have been 42
Expected: True
Actual: False
Stack Trace:
RemoteInvokeHandle.Dispose(Boolean disposing) line 237
RemoteInvokeHandle.Dispose() line 58