chore(core): separate L2 Integration test CI from the L1 CI (#1242)

**Motivation**

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**Description**

<!-- A clear and concise general description of the changes this PR
introduces -->

<!-- Link to issues: Resolves #111, Resolves #222 -->

.github/workflows/ci.yaml

@@ -68,12 +68,6 @@ jobs:
         run: |
           make download-test-vectors
 
-      - name: Run L2 integration test
-        run: |
-          cd crates/l2
-          cp .env.example .env
-          make test
-
       - name: Run tests
         run: |
           make test

.github/workflows/ci_l2.yaml

@@ -0,0 +1,40 @@
+name: CI L2
+on:
+  merge_group:
+  pull_request:
+    branches: ["**"]
+    paths-ignore:
+      - "README.md"
+      - "LICENSE"
+      - "**/README.md"
+      - "**/docs/**"
+      - "crates/vm/levm/**" # We ran this in a separate workflow
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+env:
+  RUST_VERSION: 1.80.1
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v4
+
+      - name: Rustup toolchain install
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: ${{ env.RUST_VERSION }}
+
+      - name: Caching
+        uses: Swatinem/rust-cache@v2
+
+      - name: Run L2 integration test
+        run: |
+          cd crates/l2
+          cp .env.example .env
+          make test