perf: align read cadence with measured DSM four-second samples

plugin/manifest.json

@@ -1,7 +1,7 @@
 {
   "id": "pigway-agent",
   "name": "PIGWay Raspberry Pi Agent",
-  "version": "1.3.1",
+  "version": "1.3.2",
   "protocol_version": 1,
   "entrypoint": "worker.py",
   "runtime": "python3",
@@ -40,6 +40,6 @@
   },
   "legacy_connection_fields": true,
   "collection": {
-    "interval_seconds": 2
+    "interval_seconds": 4
   }
 }

tests/test_metrics.py

@@ -21,13 +21,13 @@ class MetricsTests(unittest.TestCase):
         self.assertEqual(values['network_rx_bytes_per_second'],0)
         self.assertEqual(values['network_tx_bytes_per_second'],1234)
         self.assertEqual(next(m['observed_at'] for m in result['metrics'] if m['key']=='network_tx_bytes_per_second'),120)
-        self.assertEqual(result['collection']['interval_seconds'],2)
+        self.assertEqual(result['collection']['interval_seconds'],4)
         self.assertTrue(result['alerts_complete'])
 
     def test_collection_minimum_and_slower_device(self):
-        self.assertEqual(worker.collection_interval({'collection':{'interval_seconds':1}}),2)
+        self.assertEqual(worker.collection_interval({'collection':{'interval_seconds':1}}),4)
         self.assertEqual(worker.collection_interval({'collection':{'interval_seconds':5}}),5)
-        self.assertEqual(worker.collection_interval({'collection':{'interval_seconds':True}}),2)
+        self.assertEqual(worker.collection_interval({'collection':{'interval_seconds':True}}),4)
 
     def test_absent_or_boolean_fields_not_invented(self):
         value={'system': {'cpu_percent': True}, 'machine':{}, 'network': {'link_speed_mbps': None, 'rx_bytes_per_second':float('nan'), 'tx_bytes_per_second':True}}