evalengine: Fix week overflow

[dbussink]

Some of the last days in the year can fall in the first week of the next year. If that happens, there are various modes when we should return 53 as the week number and not week 1 for the next year.

This can always be 53. There are weeks which already contain 53 weeks, but it can never be 54 in those cases as in years with 53 weeks, there's never a last day of the year that falls in the first week of next year. It then always falls in week 53 already.

Related Issue(s)

Fixes #14858

Backporting as this is a straight bug in the calculation and it's trivially easy to fix. There's no risk to this fix either. It also can trigger CI instability if we don't fix it which is a useful reason as well.

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[vitess-bot]

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