docs: remove redundant bigquery_update_table_expiration code sample

[tswast]

New version of this sample added in #1457 and migrated to in the docs in internal change 570781706.

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Fixes #<issue_number_goes_here> 🦕

[snippet-bot]

Here is the summary of changes.

You are about to delete 1 region tag.

• docs/snippets.py:227, tag bigquery_update_table_expiration

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