Missing preview and daily build symbols #71735
Description
Installing .NET 7 preview 4 from https://dot.net/core, or a daily build (currently 7.0.100-preview.6.22310.18) from https://github.com/dotnet/installer#table results in missing symbols.
$ dotnet --version
7.0.100-preview.4.22252.9
$ dotnet new console -n test1; cd test1
$ dotnet publish -c Release --use-current-runtime -p:PublishSingleFile=true --self-contained -o dist
$ dotnet-symbol dist/test1
Downloading from http://msdl.microsoft.com/download/symbols/
ERROR: Not Found: singlefilehost.dbg - 'http://msdl.microsoft.com/download/symbols/_.debug/elf-buildid-sym-c75bf0aead43cc1afd9ba0107160b306887c48c6/_.debug'$ dotnet --version
7.0.100-preview.6.22310.18
$ dotnet new console -n test1; cd test1
$ dotnet publish -c Release --use-current-runtime -p:PublishSingleFile=true --self-contained -o dist
$ dotnet-symbol dist/test1
Downloading from http://msdl.microsoft.com/download/symbols/
ERROR: Not Found: singlefilehost.dbg - 'http://msdl.microsoft.com/download/symbols/_.debug/elf-buildid-sym-2817019b497524659815d8f68078034d75098be4/_.debug'