[dotnet] Simply script to internally use `https://dot.net/v1/dotnet-install.sh`

[joshspicer]

The existing dotnet-install.sh script maintained by the dotnet team is really reliable and works well - we should refactor the dotnet script to simply use this script in all cases for simplicity

https://learn.microsoft.com/en-us/dotnet/core/tools/dotnet-install-script

This should also fix what #297 attempted to solve