Fix code-coverage llvm-tools install (#18624)

## Description 

Describe the changes or additions included in this PR.

## Test plan 

How did you test the new or updated feature?

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:

.github/workflows/cargo-llvm-cov.yml

@@ -36,6 +36,9 @@ jobs:
     env:
       CARGO_TERM_COLOR: always
     steps:
+      - name: Install Rust
+        run: rustup update stable
+
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11  # Pin v4.1.1
       - uses: bmwill/rust-cache@v1
 
@@ -49,9 +52,6 @@ jobs:
         uses: pierotofy/set-swap-space@master
         with:
           swap-size-gb: 256
-
-      - name: Install Rust
-        run: rustup update stable
 
       - name: Run code coverage for nextest
         run: SUI_SKIP_SIMTESTS=1 cargo llvm-cov --ignore-run-fail --lcov --output-path lcov.info nextest