chore: fix concurrent CommitQuota transactions for unrelated users/orgs (#15261)

The failure condition being fixed is `w1` and `w2` could belong
to different users, organizations, and templates and still cause a
serializable failure if run concurrently. This is because the old query 
did a `seq scan` on the `workspace_builds` table. Since that is the 
table being updated, we really want to prevent that.

So before this would fail for any 2 workspaces. Now it only fails if
`w1` and `w2` are owned by the same user and organization.

coderd/database/dbmetrics/querymetrics.go

@@ -66,6 +66,13 @@ func (m queryMetricsStore) Ping(ctx context.Context) (time.Duration, error) {
 	return duration, err
 }
 
+func (m queryMetricsStore) PGLocks(ctx context.Context) (database.PGLocks, error) {
+	start := time.Now()
+	locks, err := m.s.PGLocks(ctx)
+	m.queryLatencies.WithLabelValues("PGLocks").Observe(time.Since(start).Seconds())
+	return locks, err
+}
+
 func (m queryMetricsStore) InTx(f func(database.Store) error, options *database.TxOptions) error {
 	return m.dbMetrics.InTx(f, options)
 }