CI: Break out some fastish Rust checks into new "build" step

.gitlab-ci.yml

@@ -36,16 +36,13 @@ maint-checks:
     - ./maint/check_toposort
     - ./maint/add_warning --check crates/*/src/{lib,main}.rs
 
-rust-latest:
+rust-checks:
+  # This is too slow (and the cacheing of the "cargo build" too flaky) to be a "check"
   stage: build
   image: rust:latest
   script:
     - rustup show
-    - cargo build --locked --verbose --target x86_64-unknown-linux-gnu
-    - cargo test --verbose --target x86_64-unknown-linux-gnu
-    - rustup component add clippy rustfmt
-    - rustup show
-    - cargo clippy --all-features --all-targets -- -D warnings
+    - rustup component add rustfmt
     - cargo fmt -- --check
     - cp cargo-license $CARGO_HOME/bin/ || cargo install cargo-license
     - ./maint/check_licenses
@@ -55,12 +52,23 @@ rust-latest:
     - cp cargo-sort $CARGO_HOME/bin/ || cargo install cargo-sort
     - ./maint/cargo_sort
     - cp $CARGO_HOME/bin/cargo-sort .
-    - cargo build --verbose --release -p arti-bench --target x86_64-unknown-linux-gnu
   cache:
     paths:
       - cargo-audit
       - cargo-sort
       - cargo-license
+
+rust-latest:
+  stage: build
+  image: rust:latest
+  script:
+    - rustup show
+    - cargo build --locked --verbose --target x86_64-unknown-linux-gnu
+    - cargo test --verbose --target x86_64-unknown-linux-gnu
+    - rustup component add clippy
+    - rustup show
+    - cargo clippy --all-features --all-targets -- -D warnings
+    - cargo build --verbose --release -p arti-bench --target x86_64-unknown-linux-gnu
   artifacts:
     paths:
       - target/x86_64-unknown-linux-gnu/debug/arti