The query condition cache key encodes only the WHERE/PREWHERE predicate,
not the SAMPLE clause. A `SELECT ... SAMPLE x WHERE cond` query reads only
the marks the sampling key selects, then records that sampling-narrowed
mark mask under the predicate hash. A later non-sampled query with the same
predicate reuses the under-counted mask, skips the marks SAMPLE excluded,
and silently returns too few rows.

Disable the query condition cache (both the index-analysis write and the
runtime PREWHERE/WHERE write) whenever the read uses sampling, mirroring
the existing FINAL / bucket_id guards in the disable-cascade.

The consult side is left unchanged: once writes are blocked during
sampling the cache only ever holds full-predicate masks, and a
predicate-false mark stays predicate-false under any sample subset, so
sampled reads still benefit from previously cached full-scan verdicts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>