sqlstats: increase default value for deleted rows

During the sql stats compaction job, we limit the amount of
rows being deleted per transaction. We used a default value
of 1024, but we have been increasinly seeing customer needing
to increase this value to allow the job to keep up with the
large amount of data being flushed.
We have been recommening a value for 20k, so being more
conservative with the default (plus the changes on cockroachdb#97123
that won't let tables get in a state with so many rows),
this commit changes the value to 10k.

Fixes cockroachdb#97528

Release note (sql change): Increase the default value of
`sql.stats.cleanup.rows_to_delete_per_txn` to 10k, to increase
efficiency of the cleanup job for sql statistics.

pkg/sql/sqlstats/persistedsqlstats/cluster_settings.go

@@ -126,6 +126,6 @@ var CompactionJobRowsToDeletePerTxn = settings.RegisterIntSetting(
 	settings.TenantWritable,
 	"sql.stats.cleanup.rows_to_delete_per_txn",
 	"number of rows the compaction job deletes from system table per iteration",
-	1024,
+	10000,
 	settings.NonNegativeInt,
 )