pgsql: Fix copy-paste error related to the autovacuum launcher in pgsta

Fix copy-paste error related to the autovacuum launcher in pgstat_io.c

Autovacuum launchers perform no WAL IO reads, but pgstat_tracks_io_op()
was tracking them as an allowed combination for the "init" and "normal"
contexts.

This caused the "read", "read_bytes" and "read_time" attributes of
pg_stat_io to show zeros for the autovacuum launcher rather than NULL.
NULL means that a combination of IO object, IO context and IO operation
has no meaning for a backend type. Zero is the same as telling that a
combination is relevant, and that WAL reads are possible in an
autovacuum launcher, but it is not relevant.

Copy-pasto introduced in a051e71e28a1.

Author: Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
Reviewed-by: Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAEudQAopEMAPiUqE7BvDV+x2fUPmKmb9RrsaoDR+hhQzLKg4PQ@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/17d8bba6dad12e14a7cafca9ef5eef21e577e9c3

Modified Files
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src/backend/utils/activity/pgstat_io.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)