cmd,service: remove temporary def of Server interface in func

Use the defination of Server interface in service package, instead of
temporary in func.

cmd/dlv/cmds/commands.go

@@ -510,10 +510,7 @@ func execute(attachPid int, processArgs []string, conf *config.Config, coreFile
 	}
 	defer listener.Close()
 
-	var server interface {
-		Run() error
-		Stop() error
-	}
+	var server service.Server
 
 	disconnectChan := make(chan struct{})
 

service/server.go

@@ -4,5 +4,5 @@ package service
 // to connect to.
 type Server interface {
 	Run() error
-	Stop(bool) error
+	Stop() error
 }