Add limit size for server/db/actor file

[Keonik1]

Hello, @adrianth

OpenTest version number: 1.3.8

If the opentest server instance is running for a long time, then after some time the server/db/actor file will start to weigh a lot, but besides the fact that the place is dealing with unnecessary data, there is also a bug that does not allow you to start the server instance if this file is larger than 500+ megabytes (in my case 560MB). To start, you will need to manually delete the file.

The request is to limit the size of this file in general, because it does not carry anything useful for administration. The size can be limited either by a couple of megabytes or by the number of rows, conditional 10000, it does not matter.

The speed of filling this file depends on the number of actors. And yes, I know that the file is cleared when the server instance is started, but the problem is that the server instance will not start if this file weighs too much.