`dotnetbuilds.blob.core.windows.net` has no anonymous access -- switch to new CDN

[richlander]

I've seen this in a few branches, related to dotnet/announcements#375

/__w/1/s/.packages/microsoft.dotnet.helix.sdk/9.0.0-beta.25555.4/tools/dotnet-cli/DotNetCli.targets(7,5): warning : Unable to resolve download link from feed https://dotnetbuilds.blob.core.windows.net/public; Response status code does not indicate success: 409 (Public access is not permitted on this storage account.). [/__w/1/s/src/libraries/sendtohelixhelp.proj]
##[warning].packages/microsoft.dotnet.helix.sdk/9.0.0-beta.25555.4/tools/dotnet-cli/DotNetCli.targets(7,5): warning : Unable to resolve download link from feed https://dotnetbuilds.blob.core.windows.net/public; Response status code does not indicate success: 409 (Public access is not permitted on this storage account.).

It seems to be specific to wasm. Does it need to reference a newer helix SDK version?

It is also worth asking the question on whether this rollout was done correctly.

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
See info in area-owners.md if you want to be subscribed.

[richlander]

@lewing