Use maintenance_io_concurrency for ANALYZE prefetch

When prefetching pages for ANALYZE, we should be using
maintenance_io_concurrenty (by calling
get_tablespace_maintenance_io_concurrency(), not
get_tablespace_io_concurrency()).

ANALYZE prefetching was introduced in c6fc50c, so back-patch to 14.

Backpatch-through: 14
Reported-By: Egor Rogov
Discussion: https://postgr.es/m/9beada99-34ce-8c95-fadb-451768d08c64%40postgrespro.ru

Author: sfrost

src/backend/commands/analyze.c

@@ -1164,7 +1164,7 @@ acquire_sample_rows(Relation onerel, int elevel,
 	nblocks = BlockSampler_Init(&bs, totalblocks, targrows, randseed);
 
 #ifdef USE_PREFETCH
-	prefetch_maximum = get_tablespace_io_concurrency(onerel->rd_rel->reltablespace);
+	prefetch_maximum = get_tablespace_maintenance_io_concurrency(onerel->rd_rel->reltablespace);
 	/* Create another BlockSampler, using the same seed, for prefetching */
 	if (prefetch_maximum)
 		(void) BlockSampler_Init(&prefetch_bs, totalblocks, targrows, randseed);