Bug 1685030 - Remove `rust` from `vscode` extensions list. r=sylvestre DONTBUILD

`rust` and `rust-analyzer` are incompatible together so we should remove the first
one since `rust-analyzer` is the better choice.

Differential Revision: https://phabricator.services.mozilla.com/D100759

.vscode/extensions.json

@@ -10,8 +10,6 @@
     "esbenp.prettier-vscode",
     // C/C++ language support with clangd
     "llvm-vs-code-extensions.vscode-clangd",
-    // Rust language support.
-    "rust-lang.rust",
     // Provides support for rust-analyzer: novel LSP server for the Rust programming language.
     "matklad.rust-analyzer",
     // CSS support for HTML documents.