refactor: make retry and timeout parameters configurable

Made retry logic and gRPC timeouts configurable across FilerClient and
MasterClient to support different deployment environments and network
conditions.

Problem 1: Hardcoded retry parameters in FilerClient
  waitTime := time.Second          // Fixed at 1s
  maxRetries := 3                  // Fixed at 3 attempts
  waitTime = waitTime * 3 / 2      // Fixed 1.5x multiplier

Different environments have different needs:
  - Unstable networks: may want more retries (5) with longer waits (2s)
  - Low-latency production: may want fewer retries (2) with shorter waits (500ms)
  - Batch processing: may want exponential backoff (2x) instead of 1.5x

Problem 2: Hardcoded gRPC timeout in MasterClient
  timeoutCtx, cancel := context.WithTimeout(ctx, 5*time.Second)

Master lookups may need different timeouts:
  - High-latency cross-region: may need 10s timeout
  - Local network: may use 2s timeout for faster failure detection

Solution for FilerClient:
  1. Added fields to FilerClientOption:
     - MaxRetries int (default: 3)
     - InitialRetryWait time.Duration (default: 1s)
     - RetryBackoffFactor float64 (default: 1.5)

  2. Added fields to FilerClient:
     - maxRetries int
     - initialRetryWait time.Duration
     - retryBackoffFactor float64

  3. Updated LookupVolumeIds to use configurable values:
     waitTime := fc.initialRetryWait
     maxRetries := fc.maxRetries
     for retry := 0; retry < maxRetries; retry++ {
       ...
       waitTime = time.Duration(float64(waitTime) * fc.retryBackoffFactor)
     }

Solution for MasterClient:
  1. Added grpcTimeout field to MasterClient (default: 5s)
  2. Initialize in NewMasterClient with 5 * time.Second default
  3. Updated masterVolumeProvider to use p.masterClient.grpcTimeout

Benefits:
  ✓ Tunable for different network conditions and deployment scenarios
  ✓ Backward compatible (defaults match previous hardcoded values)
  ✓ No breaking changes to existing code
  ✓ Consistent configuration pattern across FilerClient and MasterClient

Example usage:
  // Fast-fail for low-latency production with stable network
  fc := wdclient.NewFilerClient(filers, dialOpt, dc, &wdclient.FilerClientOption{
    MaxRetries:         2,
    InitialRetryWait:   500 * time.Millisecond,
    RetryBackoffFactor: 2.0,  // Exponential backoff
    GrpcTimeout:        2 * time.Second,
  })

  // Patient retries for unstable network or batch processing
  fc := wdclient.NewFilerClient(filers, dialOpt, dc, &wdclient.FilerClientOption{
    MaxRetries:         5,
    InitialRetryWait:   2 * time.Second,
    RetryBackoffFactor: 1.5,
    GrpcTimeout:        10 * time.Second,
  })

Note: MasterClient timeout is currently set at construction time and not
user-configurable via NewMasterClient parameters. Future enhancement could
add a MasterClientOption struct similar to FilerClientOption.

weed/wdclient/masterclient.go

@@ -35,7 +35,7 @@ func (p *masterVolumeProvider) LookupVolumeIds(ctx context.Context, volumeIds []
 	glog.V(2).Infof("Looking up %d volumes from master: %v", len(volumeIds), volumeIds)
 
 	// Use a timeout for the master lookup to prevent indefinite blocking
-	timeoutCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	timeoutCtx, cancel := context.WithTimeout(ctx, p.masterClient.grpcTimeout)
 	defer cancel()
 
 	err := pb.WithMasterClient(false, p.masterClient.GetMaster(timeoutCtx), p.masterClient.grpcDialOption, false, func(client master_pb.SeaweedClient) error {
@@ -113,6 +113,7 @@ type MasterClient struct {
 	currentMasterLock sync.RWMutex
 	masters           pb.ServerDiscovery
 	grpcDialOption    grpc.DialOption
+	grpcTimeout       time.Duration // Timeout for gRPC calls to master
 	OnPeerUpdate      func(update *master_pb.ClusterNodeUpdate, startFrom time.Time)
 	OnPeerUpdateLock  sync.RWMutex
 }
@@ -125,6 +126,7 @@ func NewMasterClient(grpcDialOption grpc.DialOption, filerGroup string, clientTy
 		rack:           rack,
 		masters:        masters,
 		grpcDialOption: grpcDialOption,
+		grpcTimeout:    5 * time.Second, // Default: 5 seconds for gRPC calls to master
 	}
 
 	// Create provider that references this MasterClient