fix: use bucket stop as timestamp for metrics bucket (#9327)

This fixes a problem where the yggdrasil-engine does not send the
correct value for bucket.start. In practice clients sends metrics every
60s and it does not matter if we use start or the stop timestamp to
resolve the nearest full hour.

Author: ivarconr

src/lib/features/metrics/client-metrics/metrics-service-v2.ts

@@ -210,7 +210,7 @@ export default class ClientMetricsServiceV2 {
                     featureName: name,
                     appName: value.appName,
                     environment: value.environment ?? 'default',
-                    timestamp: value.bucket.start, //we might need to approximate between start/stop...
+                    timestamp: value.bucket.stop, //we might need to approximate between start/stop...
                     yes: value.bucket.toggles[name].yes ?? 0,
                     no: value.bucket.toggles[name].no ?? 0,
                     variants: value.bucket.toggles[name].variants,