…ke `Tuple`

`convertToFullIfNeeded` (made recursive in #97493) strips `LowCardinality`
from inner subcolumns of compound types (Tuple, Array, etc.) in
`Set::insertFromColumns`, but `set_elements_types` in `Set::setHeader`
only stripped top-level `LowCardinality`. This created a column/type
mismatch: `ColumnVector<Int8>` in the column vs `LowCardinality(Int8)`
in the type.

When `KeyCondition::tryPrepareSetColumnsForIndex` unpacked the tuple to
build index conditions for `IN` subqueries, `castColumn` tried to
interpret the plain column as `ColumnLowCardinality`, causing a
LOGICAL_ERROR exception in debug builds.

Fix by using `recursiveRemoveLowCardinality` for `set_elements_types` in
both `Set::setHeader` and the static `Set::getElementTypes`, matching
what `convertToFullIfNeeded` does to columns.

https://s3.amazonaws.com/clickhouse-test-reports/json.html?PR=97831&sha=6f56284303c16ecc5f5a437491c661d5019f2977&name_0=PR&name_1=AST%20fuzzer%20%28amd_debug%29

Co-Authored-By: Claude Opus 4.6 <[email protected]>

…variant

Regression test for #97847:
`Dynamic` column with `LowCardinality` variant and `enable_join_runtime_filters`
caused LOGICAL_ERROR "Bad cast from type DB::ColumnVector<int> to
DB::ColumnLowCardinality" because `Set` stored columns with inner
`LowCardinality` stripped but `set_elements_types` still contained it inside
the `Dynamic` type. Already fixed by the previous commit.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

…al corruption

`convertToFullIfNeeded` recursively strips `LowCardinality` from subcolumns,
including variant columns inside `ColumnDynamic`. But it cannot update
`ColumnDynamic::variant_info` type metadata, creating a mismatch: variant
columns have LC stripped from data while `variant_info` still references LC
types. This caused LOGICAL_ERROR in `Set::appendSetElements` when
`ColumnDynamic::insertRangeFrom` tried to serialize values using LC
serialization against non-LC column data.

Fix: override `convertToFullIfNeeded` in `ColumnDynamic` to return itself
without recursing into subcolumns. Dynamic is a self-contained typed container
that manages its own variant types.

Also add `max_threads=1` to the test for issue #97847 to reliably trigger the
runtime filter code path that exercises this bug.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

…/type mismatches

Same issue as `ColumnDynamic`: `convertToFullIfNeeded` recursively strips
`LowCardinality` from `ColumnVariant`'s internal variant sub-columns, but
cannot update the corresponding `DataTypeVariant` (which sorts variants by
name). This creates column/type position mismatches that cause LOGICAL_ERROR
in `KeyCondition::tryPrepareSetColumnsForIndex` when casting set elements
for index conditions.

Fix: override `convertToFullIfNeeded` in `ColumnVariant` to return itself
without recursing into sub-columns, matching the approach for `ColumnDynamic`.

Closes #97854

Co-Authored-By: Claude Opus 4.6 <[email protected]>

…ormat-variant-low-cardinality

Fix LOGICAL_ERROR exceptions from recursive `convertToFullIfNeeded` with `LowCardinality` inside compound types