[scheduler] Fix bug on limits query (#2253)

A missing parenthesis meant we're querying limits for way more than the
single layer we're interested in.


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-->

## Summary by CodeRabbit

* **Bug Fixes**
* Corrected layer limit validation to ensure conditions are properly
evaluated for accurate threshold compliance assessment.

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Author: DiegoTavares

rust/crates/scheduler/src/dao/layer_dao.rs

@@ -451,8 +451,8 @@ impl LayerDao {
                     GROUP BY limit_record.pk_limit_record
                 ) AS sum_running ON limit_record.pk_limit_record = sum_running.pk_limit_record
                 WHERE layer.pk_layer = $1
-                    AND sum_running.int_sum_running < limit_record.int_max_value
-                    OR sum_running.int_sum_running IS NULL
+                    AND (sum_running.int_sum_running < limit_record.int_max_value
+                        OR sum_running.int_sum_running IS NULL)
         "#,
         )
         .bind(layer.id.to_string())