chore: updating spark registry and tags on examples and docs

[brito-rafa]

See issue #1868.
Updating the examples and docs to reduce the friction to new users.
The accessible container registry and tag is apache/spark:v3.1.3 with spark version 3.1.3.
The examples point to older version 3.1.1 no longer exist and pods fail with ImagePullBackOff.

Update: signed the cla.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

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[yuchaoran2011]

@brito-rafa Please sign the CLA and then the PR should be good to be merged

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: brito-rafa
Once this PR has been reviewed and has the lgtm label, please assign mwielgus for approval. For more information see the Kubernetes Code Review Process.

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[brito-rafa]

I had signed to the CLA, but just to make sure, I re-signed with my personal email as well.

[yuchaoran2011]

@brito-rafa Please have a look at the CI checks. Two failed: CLA needs to be signed and merge conflicts need to be resolved

[brito-rafa]

Closing this one in favor of #2010