ci(kernel-e2e): disable bundled rust-cache in setup-rust-toolchain

actions-rust-lang/setup-rust-toolchain invokes Swatinem/rust-cache
internally, which runs `cargo metadata` from the workflow's working
directory. Our job's CWD is the connector repo root (no Cargo.toml
there — the kernel checkout is in a subdir), so the bundled cache
attempt fails with exit 101 and dumps a Node stack trace into the
log. It's cosmetic — the action handles its own errors — but reads
as a failure on first glance, and the bundled cache races with the
explicit rust-cache step we already configure with the correct
`workspaces: databricks-sql-kernel` path.

Disabling the bundled cache leaves a single, correctly-keyed
rust-cache invocation and cleans up the log.

Co-authored-by: Isaac
Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>

Author: vikrantpuppala

.github/workflows/kernel-e2e.yml

@@ -254,6 +254,13 @@ jobs:
       # are on PATH when the kernel build step runs.
       - name: Set up Rust toolchain
         uses: actions-rust-lang/setup-rust-toolchain@1780873c7b576612439a134613cc4cc74ce5538c # v1.15.2
+        with:
+          # Disable the bundled Swatinem/rust-cache invocation; it tries
+          # `cargo metadata` from the connector repo root (no Cargo.toml)
+          # and dumps a scary-looking exit-101 stack into the log even
+          # though the action ignores it. We run our own rust-cache step
+          # below with the correct workspaces path.
+          cache: false
 
       - name: Cache cargo build artifacts (keyed on kernel SHA)
         uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0