💚 update browser-sdk CI workflow to use yarn github dependency

The rum-events-format submodule in browser-sdk was replaced with a yarn
github dependency. The old step that checked out the submodule at the
current SHA is replaced by `node scripts/json-schemas.ts --update <branch>
--build`, which handles resolving and building the dependency directly.

Author: BenoitZugmeyer

.github/workflows/browser-sdk.yml

@@ -17,17 +17,15 @@ jobs:
 
       - uses: actions/setup-node@1d0ff469b7ec7b3cb9d8673fde0c81c44821de2a
         with:
-          node-version: 23
+          node-version: 26
 
       - name: Install dependencies
         run: yarn
 
       - name: Update rum-events-format
-        run: |
-          cd rum-events-format
-          git checkout ${{ github.sha }}
-          cd ..
-          yarn json-schemas:generate
+        run: node scripts/json-schemas.ts --update ${{ github.sha }} --build
+        env:
+          YARN_ENABLE_IMMUTABLE_INSTALLS: false
 
       - name: Run ${{matrix.test_type}} tests
         run: eval $command_${{matrix.test_type}}