[CI] Disable unified build

The short integration test build is a unified build so this is
redundant.

.github/workflows/buildAndTest.yml

@@ -120,32 +120,6 @@ jobs:
 
   # --- end of sanity-check job.
 
-  # Configure CIRCT using LLVM's build system ("Unified" build). We do not actually build this configuration since it isn't as easy to cache LLVM artifacts in this mode.
-  configure-circt-unified:
-    name: Configure Unified Build
-    runs-on: ubuntu-20.04
-    steps:
-      # Clone the CIRCT repo and its submodules. Do shallow clone to save clone
-      # time.
-      - name: Get CIRCT
-        uses: actions/checkout@v3
-        with:
-          fetch-depth: 2
-          submodules: "true"
-
-      - name: Configure Unified Build
-        run: |
-          mkdir configure_unified
-          cd configure_unified
-          cmake ../llvm/llvm \
-            -DCMAKE_BUILD_TYPE=Release \
-            -DBUILD_SHARED_LIBS=ON \
-            -DLLVM_ENABLE_PROJECTS=mlir \
-            -DLLVM_TARGETS_TO_BUILD=host \
-            -DLLVM_ENABLE_ASSERTIONS=ON \
-            -DLLVM_EXTERNAL_PROJECTS=circt \
-            -DLLVM_EXTERNAL_CIRCT_SOURCE_DIR=$PWD/..
-
   # --- end of configure-circt-unified job.
 
   # Build CIRCT and run its tests.