Fix biuld variables being deleted by porter form key value array

dashboard/src/components/porter-form/field-components/KeyValueArray.tsx

@@ -511,6 +511,10 @@ export const getFinalVariablesForKeyValueArray: GetFinalVariablesFunction = (
       }
     });
 
+    if (Array.isArray(props.value) && props.value[0]?.build) {
+      obj.build = props.value[0].build;
+    }
+
     if (state.synced_env_groups?.length) {
       obj.synced = state.synced_env_groups.map((envGroup) => ({
         name: envGroup?.name,