gh-119123: Fix sniffer to understand csv lists

[aterrel]

• Issue: The CSV file delimiter found with csv.Sniffer() is interpreted incorrectly #119123

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[aterrel]

@bedevere-app I don't think this needs a news entry

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[bedevere-app]

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[aterrel]

@serhiy-storchaka can you review this PR, Thanks!

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[serhiy-storchaka]

Thank you, but I do not think that this is the right approach.

Removing [...] from the sample teaches the sniffer one particular data syntax, and leaves the underlying problem: a character adjacent to a quoted run was counted as evidence of a delimiter even when it does not delimit anything. On the main branch the sniffer was rewritten (gh-83273) and this code no longer exists; a fix for the maintenance branches should not depend on the format of the data.