Stop using cargo-ensure-installed (#10400)

As of rust 1.45.0, cargo will no-op if you try to re-install a package
you already have installed, if you request an exact version match, so
cargo-ensure-installed is no longer necessary.

build-support/bin/check_rust_target_headers.sh

@@ -4,7 +4,7 @@ REPO_ROOT="$(git rev-parse --show-toplevel)"
 
 cargo="${REPO_ROOT}/build-support/bin/native/cargo"
 
-"${cargo}" ensure-installed --package cargo-ensure-prefix --version 0.1.3
+"${cargo}" install cargo-ensure-prefix --version "=0.1.3"
 
 if ! out="$("${cargo}" ensure-prefix \
   --manifest-path="${REPO_ROOT}/src/rust/engine/Cargo.toml" \

build-support/bin/native/bootstrap_rust.sh

@@ -43,7 +43,6 @@ function bootstrap_rust() {
     curl --fail https://sh.rustup.rs -sS | sh -s -- -y --no-modify-path --default-toolchain none 1>&2
   fi
 
-  local -r cargo="${CARGO_HOME}/bin/cargo"
   local -r cargo_components_fp=$(echo "${RUST_COMPONENTS[@]}" | fingerprint_data)
   local -r cargo_versioned="cargo-${RUST_TOOLCHAIN}-${cargo_components_fp}"
   if [[ ! -x "${rust_toolchain_root}/${cargo_versioned}" || "${RUST_TOOLCHAIN}" == "nightly" ]]; then
@@ -57,11 +56,6 @@ function bootstrap_rust() {
     ln -fs "${symlink_target}" "${rust_toolchain_root}/${cargo_versioned}"
   fi
 
-  if [[ ! -x "${CARGO_HOME}/bin/cargo-ensure-installed" ]]; then
-    "${cargo}" install cargo-ensure-installed
-  fi
-  "${cargo}" ensure-installed --package cargo-ensure-installed --version 0.2.1
-
   local -r symlink_farm_root="${REPO_ROOT}/build-support/bin/native"
   if [[ ! -x "${symlink_farm_root}/.${cargo_versioned}" ]]; then
     (