ILike with no wildcards is mistakenly optimized to string equality

### Describe the bug

`col ILIKE 'A'` ends up evaluating as false.

Edit: Correction: `'a' ILIKE 'A'` seems to get constant-folded, so it wouldn't trigger the bug.  `col ILIKE 'A'` does.

One reproducing query on 46.0.1: `SELECT s.col ILIKE 'A' FROM (SELECT 'a' AS col) AS s`

PR incoming.

### To Reproduce

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### Expected behavior

_No response_

### Additional context

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