sql: fix logic to collect stats on system.jobs

This commit fixes an oversight in cockroachdb#102637 which intended to enable
stats collection on the jobs table, but was not successful.

I've manually confirmed that stats are now collected on the jobs table
in a local cluster:
```
  888074673664065537 | AUTO CREATE STATS               | Table statistics refresh for system.public.jobs                         | CREATE STATISTICS __auto__ FROM [15] WITH OPTIONS THROTTLING 0.9 AS OF SYSTEM TIME '-30s'  | root      | succeeded | NULL           | 2023-08-03 19:01:22.343
```

Informs cockroachdb#107405

Release note (performance improvement): We now automatically collect
table statistics on the system.jobs table, which will enable the optimizer
to produce better query plans for internal queries that access the
system.jobs table. This may result in better performance of the system.
Note: a previous attempt to enable stats on system.jobs starting in 23.1.0
was unsuccessful, but we have now fixed the oversight.

Author: rytaft

pkg/sql/create_stats.go

@@ -233,12 +233,6 @@ func (n *createStatsNode) makeJobRecord(ctx context.Context) (*jobs.Record, erro
 		)
 	}
 
-	if tableDesc.GetID() == keys.JobsTableID {
-		return nil, pgerror.New(
-			pgcode.WrongObjectType, "cannot create statistics on system.jobs",
-		)
-	}
-
 	if tableDesc.GetID() == keys.ScheduledJobsTableID {
 		return nil, pgerror.New(
 			pgcode.WrongObjectType, "cannot create statistics on system.scheduled_jobs",

pkg/sql/logictest/testdata/logic_test/distsql_stats

@@ -1657,8 +1657,8 @@ ANALYZE system.lease
 statement error pq: cannot create statistics on system.table_statistics
 ANALYZE system.table_statistics
 
-# Collecting stats on system.jobs is disallowed.
-statement error pq: cannot create statistics on system.jobs
+# Collecting stats on system.jobs is allowed.
+statement ok
 ANALYZE system.jobs
 
 # Collecting stats on system.scheduled_jobs is disallowed.