Remove Windows PDB conversion

https://github.com/dotnet/arcade/blob/490307dc9bb09caf016b2fa96005ac8aaa89c4e7/src/Microsoft.DotNet.Arcade.Sdk/tools/ProjectDefaults.props#L32-L33

Windows PDBs were originally produced to support tools like WinDbg and Watson. From what I see, both of these tools already support portable PDBs. I.e.: https://github.com/MicrosoftDocs/windows-driver-docs/blob/staging/windows-driver-docs-pr/debugger/symbols-portable-pdb.md#portable-pdb-symbols

Roslyn, razor and maybe others also don't produce them anymore: https://github.com/dotnet/roslyn/pull/64581

Unless someone still knows reasons to keep producing Windows PDBs, we should disable the conversion and remove the associated infrastructure. Bonus: This also removes differences in the VMR build which currently disables the windows PDB generation in three repos: https://github.com/search?q=repo%3Adotnet%2Fsdk%20PublishWindowsPdb&type=code

cc @mmitche @akoeplinger @tmat