refactor: remove unused gRPC connection age parameters (#7852)

The GrpcMaxConnectionAge and GrpcMaxConnectionAgeGrace constants have a troubled
history - they were removed in 2022 due to gRPC issues, reverted later, and
recently re-added. However, they are not essential to the core worker reconnection
fix which was solved through proper goroutine ordering.

The Docker Swarm DNS handling mentioned in the comments is not critical, and
these parameters have caused problems in the past. Removing them simplifies
the configuration without losing functionality.

weed/pb/grpc_client_server.go

@@ -35,11 +35,6 @@ const (
 	// gRPC keepalive settings - must be consistent between client and server
 	GrpcKeepAliveTime    = 60 * time.Second // ping interval when no activity
 	GrpcKeepAliveTimeout = 20 * time.Second // ping timeout
-
-	// Connection recycling for Docker Swarm environments
-	// Forces connections to be recycled periodically to handle DNS changes
-	GrpcMaxConnectionAge      = 5 * time.Minute  // max time a connection may exist
-	GrpcMaxConnectionAgeGrace = 30 * time.Second // grace period for RPCs to complete
 )
 
 var (
@@ -63,10 +58,8 @@ func NewGrpcServer(opts ...grpc.ServerOption) *grpc.Server {
 	var options []grpc.ServerOption
 	options = append(options,
 		grpc.KeepaliveParams(keepalive.ServerParameters{
-			Time:                  GrpcKeepAliveTime,         // server pings client if no activity for this long
-			Timeout:               GrpcKeepAliveTimeout,      // ping timeout
-			MaxConnectionAge:      GrpcMaxConnectionAge,      // max connection age for Docker Swarm DNS refresh
-			MaxConnectionAgeGrace: GrpcMaxConnectionAgeGrace, // grace period for in-flight RPCs
+			Time:    GrpcKeepAliveTime,    // server pings client if no activity for this long
+			Timeout: GrpcKeepAliveTimeout, // ping timeout
 		}),
 		grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
 			MinTime:             GrpcKeepAliveTime, // min time a client should wait before sending a ping