fix(plugin/worker): make VacuumHandler report MaxExecutionConcurrency from worker startup flag (#8435)

* fix(plugin/worker): make VacuumHandler report MaxExecutionConcurrency from worker startup flag

Previously, MaxExecutionConcurrency was hardcoded to 2 in VacuumHandler.Capability().
The scheduler's schedulerWorkerExecutionLimit() takes the minimum of the UI-configured
PerWorkerExecutionConcurrency and the worker-reported capability limit, so the hardcoded
value silently capped each worker to 2 concurrent vacuum executions regardless of the
--max-execute flag passed at worker startup.

Pass maxExecutionConcurrency into NewVacuumHandler() and wire it through
buildPluginWorkerHandler/buildPluginWorkerHandlers so the capability reflects the actual
worker configuration. The default falls back to 2 when the value is unset or zero.

* Update weed/command/worker_runtime.go

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Anton Ustyugov <anton@devops>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

weed/plugin/worker/vacuum_handler.go

@@ -22,25 +22,37 @@ import (
 )
 
 const (
-	defaultVacuumTaskBatchSize = int32(1000)
+	defaultVacuumTaskBatchSize     = int32(1000)
+	DefaultMaxExecutionConcurrency = int32(2)
 )
 
 // VacuumHandler is the plugin job handler for vacuum job type.
 type VacuumHandler struct {
-	grpcDialOption grpc.DialOption
+	grpcDialOption          grpc.DialOption
+	maxExecutionConcurrency int32
 }
 
-func NewVacuumHandler(grpcDialOption grpc.DialOption) *VacuumHandler {
-	return &VacuumHandler{grpcDialOption: grpcDialOption}
+// NewVacuumHandler creates a VacuumHandler with the given gRPC dial option and
+// maximum execution concurrency. When maxExecutionConcurrency is zero or
+// negative, DefaultMaxExecutionConcurrency is used as the fallback.
+func NewVacuumHandler(grpcDialOption grpc.DialOption, maxExecutionConcurrency int32) *VacuumHandler {
+	return &VacuumHandler{grpcDialOption: grpcDialOption, maxExecutionConcurrency: maxExecutionConcurrency}
 }
 
+// Capability returns the job type capability for the vacuum handler.
+// MaxExecutionConcurrency reflects the value passed at construction time,
+// falling back to DefaultMaxExecutionConcurrency when unset.
 func (h *VacuumHandler) Capability() *plugin_pb.JobTypeCapability {
+	maxExec := h.maxExecutionConcurrency
+	if maxExec <= 0 {
+		maxExec = DefaultMaxExecutionConcurrency
+	}
 	return &plugin_pb.JobTypeCapability{
 		JobType:                 "vacuum",
 		CanDetect:               true,
 		CanExecute:              true,
 		MaxDetectionConcurrency: 1,
-		MaxExecutionConcurrency: 2,
+		MaxExecutionConcurrency: maxExec,
 		DisplayName:             "Volume Vacuum",
 		Description:             "Reclaims disk space by removing deleted files from volumes",
 	}

weed/plugin/worker/vacuum_handler_test.go

@@ -141,7 +141,7 @@ func TestShouldSkipDetectionByInterval(t *testing.T) {
 }
 
 func TestVacuumHandlerRejectsUnsupportedJobType(t *testing.T) {
-	handler := NewVacuumHandler(nil)
+	handler := NewVacuumHandler(nil, 0)
 	err := handler.Detect(context.Background(), &plugin_pb.RunDetectionRequest{
 		JobType: "balance",
 	}, noopDetectionSender{})
@@ -158,7 +158,7 @@ func TestVacuumHandlerRejectsUnsupportedJobType(t *testing.T) {
 }
 
 func TestVacuumHandlerDetectSkipsByMinInterval(t *testing.T) {
-	handler := NewVacuumHandler(nil)
+	handler := NewVacuumHandler(nil, 0)
 	sender := &recordingDetectionSender{}
 	err := handler.Detect(context.Background(), &plugin_pb.RunDetectionRequest{
 		JobType:           "vacuum",