feat(worker): expose task completion rate in worker heartbeat

[fhussonnois]

Add a per-Worker RateMeter that derives the task completion rate (tasks/sec) from the existing worker.ended.count counter — EWMA-smoothed (ALPHA=0.3), sampled on each heartbeat and emitted as the worker.tasks.rate metric in the heartbeat set. No new Micrometer meter is registered; the rate is an operational figure for the Worker Group UI only.

[github-actions]

📄 OpenAPI Spec Changes

Spec generated with EE branch feat/worker-group-throughput. Diff vs client-sdk:

24572a24573,24575
>         endedRate:
>           type: number
>           format: double
24621a24625,24627
>         totalEndedRate:
>           type: number
>           format: double

🐋 Docker image

ghcr.io/kestra-io/kestra-pr:16865

docker run --pull=always --rm -it -p 8080:8080 --user=root -v /var/run/docker.sock:/var/run/docker.sock -v /tmp:/tmp ghcr.io/kestra-io/kestra-pr:16865 server local

🧪 Java Unit Tests

	Tests	Passed ☑️	Skipped ⚠️	Failed ❌️	Time ⏱
Java Tests Report	6945 ran	6924 ✅	20 ⚠️	1 ❌	52m 38s 962ms

Test	Result	Time ⏱
Java Tests Report
GrpcWorkerIOSenderTest.shouldRequeueAndRedeliverWhenSendFailsWithRetryableError()	❌ failure	6s 192ms

[github-actions]

Tests report quick summary:

failed ❌ > tests: 6945, success: 6924, skipped: 20, failed: 1 (🔄 6945 executed, 📦 0 from cache)

Project	Status	Success	Skipped	Failed
cli	success ✅ 🔄	55	1	0
core	success ✅ 🔄	2686	6	0
executor	success ✅ 🔄	70	3	0
jdbc	success ✅ 🔄	30	6	0
jdbc-h2	success ✅ 🔄	912	1	0
jdbc-mysql	success ✅ 🔄	903	2	0
jdbc-postgres	success ✅ 🔄	917	0	0
processor	success ✅ 🔄	7	0	0
queue	success ✅ 🔄	39	0	0
runner-memory	success ✅ 🔄	1	0	0
scheduler	success ✅ 🔄	99	0	0
script	success ✅ 🔄	37	0	0
storage-local	success ✅ 🔄	66	0	0
tests	success ✅ 🔄	2	0	0
webserver	success ✅ 🔄	901	1	0
worker	failed ❌ 🔄	64	0	1
worker-controller	success ✅ 🔄	135	0	0

Failed tests:

worker > io.kestra.worker.senders.GrpcWorkerIOSenderTest > shouldRequeueAndRedeliverWhenSendFailsWithRetryableError() failed ❌ in 6.192

org.mockito.exceptions.verification.TooFewActualInvocations: &#10;grpcWorkerControllerService.sendWorkerTaskResults(&#10;    <Capturing argument: OpaqueData>,&#10;    <any>&#10;);&#10;Wanted *at least* 2 times:&#10;-> at io.kestra.controller.grpc.services.GrpcWorkerControllerService.sendWorkerTaskResults(GrpcWorkerControllerService.java:193)&#10;But was 1 time:&#10;-> at io.kestra.worker.senders.$GrpcWorkerIOSenderTest$GrpcWorkerControllerService0$Definition$Exec.dispatch(Unknown Source)&#10;

org.mockito.exceptions.verification.TooFewActualInvocations: 
grpcWorkerControllerService.sendWorkerTaskResults(
    <Capturing argument: OpaqueData>,
    <any>
);
Wanted *at least* 2 times:
-> at io.kestra.controller.grpc.services.GrpcWorkerControllerService.sendWorkerTaskResults(GrpcWorkerControllerService.java:193)
But was 1 time:
-> at io.kestra.worker.senders.$GrpcWorkerIOSenderTest$GrpcWorkerControllerService0$Definition$Exec.dispatch(Unknown Source)

	at io.kestra.controller.grpc.services.GrpcWorkerControllerService.sendWorkerTaskResults(GrpcWorkerControllerService.java:193)
	at io.kestra.worker.senders.GrpcWorkerIOSenderTest.lambda$shouldRequeueAndRedeliverWhenSendFailsWithRetryableError$1(GrpcWorkerIOSenderTest.java:192)
	at org.awaitility.core.AssertionCondition.lambda$new$0(AssertionCondition.java:53)
	at org.awaitility.core.ConditionAwaiter$ConditionPoller.call(ConditionAwaiter.java:248)
	at org.awaitility.core.ConditionAwaiter$ConditionPoller.call(ConditionAwaiter.java:235)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:328)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614)
	at java.base/java.lang.Thread.run(Thread.java:1474)

---

Develocity build scan: https://develocity.kestra.io/s/pwwepivrfmvde

---

Flaky tests report quick summary:

success ✅ > tests: 13, success: 13, skipped: 0, failed: 0

unfold for details

Project	Status	Success	Skipped	Failed
cli	success ✅	2	0	0
jdbc-h2	success ✅	1	0	0
jdbc-mysql	success ✅	2	0	0
jdbc-postgres	success ✅	1	0	0
script	success ✅	2	0	0
webserver	success ✅	5	0	0

[ammeek]

LGTM