fix: change ts_query definition to avoid double-stemming

[smcdonald-jus]

Description

Fixes #19580

When performing sparse queries with words ending in double-E's (such as refugee), relevant database entries would not be returned. This is because the Snowball stemmer is not idempotent on double-E words (i.e. stem(stem('refugee')) 'refug' != stem('refugee') = 'refugee', and the query was being stemmed twice while the database entries were stemmed only once.

This is a consequence of the definition of ts_query, which first transformed the string into a ts query, then to text so the AND operators could be replaced with OR operators, and finally back into a ts query.

Instead, we can replace the spaces with "|"'s in the initial query string, so that the to_tsquery transformation need only be applied once. This will ensure an OR query while stemming only one time.

Note: this assumes English stemming and may have unintended consequences for other languages/encodings, depending on how spaces work in the corresponding Snowball stemmers.

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Type of Change

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• Bug fix (non-breaking change which fixes an issue)

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