vscode: fix upstream domain name

[wesleywright]

The VS Code team recently retired a deprecated domain used for VS Code downloads. This breaks update-vscode.sh and customized package installations (such as used by home-manager). The new domain name is the one preferred by the VS Code team, as stated in this GitHub issue: microsoft/vscode#119822

Motivation for this change

All builds of the vscode package are currently broken.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[wesleywright]

I haven't tested extensively (and I'm relatively new to Nix and not sure how to use sandboxing for a one-off build with my current setup), but I should note that I didn't change any of the pinned checksums and the build completes successfully. I expect this should have 0 impact on build or runtime behavior (beyond the download succeeding instead of failing).