fix: remove cleanup stop step — composite actions run inline, stopping buildkitd before the build

The 'Stop BuildKit (idle cleanup)' step executed immediately after setup
(composite action steps are not deferred to job end; always() does not
create a post-step), so every downstream buildx build failed with
'waiting for connection: context deadline exceeded'.

action.yml

@@ -17,10 +17,6 @@ inputs:
     description: 'Value for dockhand.notify'
     required: false
     default: 'false'
-  cleanup:
-    description: 'Stop the buildkitd container after the job (idle cleanup; container restarts on demand on the next run)'
-    required: false
-    default: 'true'
   network:
     description: 'Docker network for the buildkitd container — MUST match the network the job containers run on, otherwise the name is unresolvable'
     required: false
@@ -58,8 +54,3 @@ runs:
         # logs), so it reaches buildkitd via the host-published loopback port.
         # Docker DNS names are NOT resolvable from the host namespace.
         endpoint: tcp://127.0.0.1:${{ inputs.port }}
-
-    - name: Stop BuildKit (idle cleanup)
-      if: ${{ inputs.cleanup == 'true' && always() }}
-      shell: bash
-      run: docker stop ${{ inputs.container_name }} || true