docs: revised relax column mode sample

[thejaredchapman]

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Towards #790 🦕

[snippet-bot]

Here is the summary of changes.

You are about to add 2 region tags.

• samples/snippets/relax_column.py:21, tag bigquery_relax_column
• samples/snippets/relax_column.py:32, tag bigquery_relax_column

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[tswast]

We should add a TODO to snippets.py (or wherever the old sample is) to remove it after updating cloud.google.com

[meredithslota]

This is missing the CLA — we can either override this (see the CLA details) or close this and open a new PR, since the CLA violations were only in merging main into this branch.

[tswast]

This is missing the CLA — we can either override this (see the CLA details) or close this and open a new PR, since the CLA violations were only in merging main into this branch.

I'll rebase and force push to drop the bad merge commits.