[ci] Avoid installing/building/testing Rust in CI

rustup, our way to installing Rust, is currently broken, breaking all CI
jobs.

Avoid installing Rust until the issue is fixed. Software builds should
continue, but skip the Rust parts.

rust-lang/rustup#2855

Signed-off-by: Philipp Wagner <phw@lowrisc.org>

ci/install-package-dependencies.sh

@@ -136,10 +136,5 @@ sudo chmod 777 /tools/verible
 tar -C /tools/verible -xf "$verible_tar" --strip-components=1
 export PATH=/tools/verible/bin:$PATH
 
-# Install Rust
-sw/vendor/rustup/rustup-init.sh -y \
-    --default-toolchain "${RUST_VERSION}"
-export PATH=$HOME/.cargo/bin:$PATH
-
 # Propagate PATH changes to all subsequent steps of the job
 echo "##vso[task.setvariable variable=PATH]$PATH"