Docker image build in parallel
# What does this PR do?

Remove `needs` in `.github/workflows/build-docker-images.yml`, as it can run in parallel now.

See this [run page](https://github.com/huggingface/transformers/actions/runs/2389099113) v.s. the [previous run page](https://github.com/huggingface/transformers/actions/runs/2388105533), with 14 mins. v.s. 40 mins.
_The documentation is not available anymore as the PR was closed or merged._<|||||>From the job run page, I saw

```
#18 exporting to image
#18 pushing layers 35.6s done
#18 pushing manifest for docker.io/huggingface/transformers-all-latest-gpu:latest@sha256:d8523684a112bff61a2899a69e06e05e26c507778df4754454b95c3dcf244012
#18 pushing manifest for docker.io/huggingface/transformers-all-latest-gpu:latest@sha256:d8523684a112bff61a2899a69e06e05e26c507778df4754454b95c3dcf244012 0.3s done
#18 DONE 289.9s
ImageID
  sha256:08ed1b5cc8db313f116b58d86292b2e109f0552737088fba4a5c672012bca3ae
Digest
  sha256:d8523684a112bff61a2899a69e06e05e26c507778df4754454b95c3dcf244012
```
so it looks fine to me. But I will run it again and verify the images on docker hub to make sure!