namedPlaceholders cannot be disabled at query level

[wellwelwel]

• As reported in #2472

When setting namedPlaceholders globally (connection level) to true, it's not possible to disable it at the query level.

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To reproduce, just uncomment this test:

https://github.com/sidorares/node-mysql2/blob/41d21ebc9bcb47df9fc84f1f37da357fd77ba5a7/test/esm/integration/named-placeholders.test.mjs#L18-L29

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The opposite will work fine:

https://github.com/sidorares/node-mysql2/blob/41d21ebc9bcb47df9fc84f1f37da357fd77ba5a7/test/esm/integration/named-placeholders.test.mjs#L31-L44