Use less bundle redirection of DOTNETHOME

[ericstj]

Today the bundle is responsible for reading and passing down an overridden DOTNETHOME value to all installers.

We could simplify this by making the MSIs just read the registry key written by the host. Further discussed here: https://github.com/dotnet/installer/issues/11999#issuecomment-925990093

ericstj/installer@f8a7441 ericstj/aspnetcore@de64bd2 ericstj/arcade@836f0ef