pgsql: Remove PgStat_KindInfo.named_on_disk

Remove PgStat_KindInfo.named_on_disk

This field is used to track if a stats kind can use a custom format
representation on disk when reading or writing its stats case. On HEAD,
this exists for replication slots stats, that need a mapping between an
internal index ID and the slot names.

named_on_disk is currently used nowhere and the callbacks
to_serialized_name and from_serialized_name are in charge of checking if
the serialization of the stats data should apply, so let's remove it.

Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/ZmKVlSX_T5YvIOsd@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b19db55bd687af243dd1edf021ffb166e5270a06

Modified Files
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src/backend/utils/activity/pgstat.c | 1 -
src/include/utils/pgstat_internal.h | 8 +-------
2 files changed, 1 insertion(+), 8 deletions(-)