simplify plugin scheduler: remove configurable IdleSleepSeconds, use constant 61s

The SchedulerConfig struct and its persistence/API were unnecessary
indirection. Replace with a simple constant (reduced from 613s to 61s)
so the scheduler re-checks for detectable job types promptly after
going idle, improving the clean-install experience.

weed/admin/plugin/config_store.go

@@ -30,7 +30,6 @@ const (
 	runsJSONFileName        = "runs.json"
 	trackedJobsJSONFileName = "tracked_jobs.json"
 	activitiesJSONFileName  = "activities.json"
-	schedulerJSONFileName   = "scheduler.json"
 	defaultDirPerm          = 0o755
 	defaultFilePerm         = 0o644
 )
@@ -54,7 +53,6 @@ type ConfigStore struct {
 	memTrackedJobs []TrackedJob
 	memActivities  []JobActivity
 	memJobDetails  map[string]TrackedJob
-	memScheduler   *SchedulerConfig
 }
 
 func NewConfigStore(adminDataDir string) (*ConfigStore, error) {
@@ -95,60 +93,6 @@ func (s *ConfigStore) BaseDir() string {
 	return s.baseDir
 }
 
-func (s *ConfigStore) LoadSchedulerConfig() (*SchedulerConfig, error) {
-	s.mu.RLock()
-	if !s.configured {
-		cfg := s.memScheduler
-		s.mu.RUnlock()
-		if cfg == nil {
-			return nil, nil
-		}
-		clone := *cfg
-		return &clone, nil
-	}
-	s.mu.RUnlock()
-
-	path := filepath.Join(s.baseDir, schedulerJSONFileName)
-	data, err := os.ReadFile(path)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return nil, nil
-		}
-		return nil, fmt.Errorf("read scheduler config: %w", err)
-	}
-
-	var cfg SchedulerConfig
-	if err := json.Unmarshal(data, &cfg); err != nil {
-		return nil, fmt.Errorf("unmarshal scheduler config: %w", err)
-	}
-	return &cfg, nil
-}
-
-func (s *ConfigStore) SaveSchedulerConfig(config *SchedulerConfig) error {
-	if config == nil {
-		return fmt.Errorf("scheduler config is nil")
-	}
-	normalized := normalizeSchedulerConfig(*config)
-
-	s.mu.Lock()
-	if !s.configured {
-		s.memScheduler = &normalized
-		s.mu.Unlock()
-		return nil
-	}
-	s.mu.Unlock()
-
-	payload, err := json.MarshalIndent(normalized, "", "  ")
-	if err != nil {
-		return fmt.Errorf("marshal scheduler config: %w", err)
-	}
-	path := filepath.Join(s.baseDir, schedulerJSONFileName)
-	if err := os.WriteFile(path, payload, defaultFilePerm); err != nil {
-		return fmt.Errorf("save scheduler config: %w", err)
-	}
-	return nil
-}
-
 func (s *ConfigStore) SaveDescriptor(jobType string, descriptor *plugin_pb.JobTypeDescriptor) error {
 	if descriptor == nil {
 		return fmt.Errorf("descriptor is nil")