fix(dev/release): update how we find .NET download URL

Closes apache#3975.

Author: lidavidm

dev/release/verify-release-candidate.sh

@@ -273,7 +273,7 @@ install_dotnet() {
   local dotnet_download_thank_you_url=https://dotnet.microsoft.com/download/thank-you/dotnet-sdk-${dotnet_version}-${dotnet_platform}-x64-binaries
   show_info "Getting .NET download URL from ${dotnet_download_thank_you_url}"
   local dotnet_download_url=$(curl -sL ${dotnet_download_thank_you_url} | \
-                                  grep 'recordManualDownload' | \
+                                  grep 'directLink' | \
                                   grep -E -o 'https://builds.dotnet[^"]+')
   if [ -z "${dotnet_download_url}" ]; then
     echo "Failed to get .NET download URL from ${dotnet_download_thank_you_url}"