Do not set executing script directory when publishing

[RikkiGibson]

Related to #49184

We should not set an entry point directory when publishing a file-based program, as the app is expected to be deployed to another machine where the entry point (source code) path will not be useful.

e.g.

// app.cs
var entryPointFilePath = AppContext.GetData("EntryPointFilePath") as string;
Console.WriteLine($"""EntryPointFilePath: {entryPointFilePath}""");

# On build machine
$ dotnet publish app.cs

# Deploy to prod machine
$ dotnet app.dll
EntryPointFilePath: # should not have a value for 'EntryPointFilePath'

[RikkiGibson]

I think this also implies the dotnet project convert result should be conditioned in a similar way. Set the "entry point file path" in ordinary builds but not when publishing.

edit: in offline discussion we think these AppContext values should not stop being produced when converting the project.