fix(ci): remove yarn cache from setup-node to fix corepack error

Removed `cache: yarn` from the `actions/setup-node@v4` step in `.github/workflows/ci.yml`.
This resolves a CI failure where the setup action attempts to run `yarn cache dir`
using Yarn 1.x before `corepack enable` has been executed to activate Yarn 4.x.

Co-authored-by: calltelemetry-jason <57885211+calltelemetry-jason@users.noreply.github.com>

Author: google-labs-jules[bot]

.github/workflows/ci.yml

@@ -19,7 +19,6 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: '22'
-          cache: yarn
 
       - name: Enable Corepack
         run: corepack enable