[github-actions] delay restoring from lfs cache in docker/build job

LFS files aren't needed for docker image build. This delays restoring the lfs files from cache until
they are needed during the testing step

.github/workflows/docker.yml

@@ -49,8 +49,8 @@ permissions:  # added using https://github.com/step-security/secure-workflows
   contents: read
 
 jobs:
-  docker:
-    name: Build docker image
+  build:
+    name: Build Docker Image
     runs-on: ubuntu-22.04
     steps:
     - name: Harden Runner
@@ -62,19 +62,6 @@ jobs:
       with:
         submodules: true
 
-    - name: Create LFS file hash list
-      run: git -C third_party/silabs/gecko_sdk lfs ls-files -l | cut -d' ' -f1 | sort > .lfs-assets-id
-
-    - name: Restore gecko_sdk LFS cache
-      uses: actions/cache@v4
-      id: lfs-cache
-      with:
-          path: .git/modules/third_party/silabs/gecko_sdk/lfs
-          key: lfs-${{ hashFiles('.lfs-assets-id') }}
-
-    - name: Git LFS Pull
-      run: git -C third_party/silabs/gecko_sdk lfs pull
-
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226 # v3.0.0
 
@@ -92,6 +79,19 @@ jobs:
         cache-from: type=gha
         cache-to: type=gha,mode=max
 
+    - name: Create LFS file hash list
+      run: git -C third_party/silabs/gecko_sdk lfs ls-files -l | cut -d' ' -f1 | sort > .lfs-assets-id
+
+    - name: Restore gecko_sdk LFS cache
+      uses: actions/cache@v4
+      id: lfs-cache
+      with:
+          path: .git/modules/third_party/silabs/gecko_sdk/lfs
+          key: lfs-${{ hashFiles('.lfs-assets-id') }}
+
+    - name: Git LFS Pull
+      run: git -C third_party/silabs/gecko_sdk lfs pull
+
     - name: Test build inside container
       run: |
         docker run -v ${{ github.workspace }}:/ot-efr32/ --user $(id -u) --rm ${{ env.TEST_TAG }} script/build --skip-silabs-apps brd4151a