[Feature] For AP process, elegant start and stop auto-scaling

[renajin]

Feature Request

Is your feature request related to a problem? Please describe:

Describe the feature you'd like: Elegant start and stop auto-scaling module, all AP request will be processed efficiently.

Describe alternatives you've considered: We divided AP requests into two categories to handle： 1.start up a long term tidb node for real-time computing, this node will handle some simple AP requests(the sql can be finished in one minute); 2.for large-scale AP, it always need much more memory, we will start a container for each SQL and shut down this container when sql completed.

Teachability, Documentation, Adoption, Migration Strategy: