[Enhancement] Add quota for low-priority controller mutations

[ShadowySpirits]

Who is this for and what problem do they have today?

A large number of compaction or delete object requests may overload the controller event loop.
We should add a mechanism to protect the controller by stopping low-priority requests and allowing it to prioritize high-priority requests, such as broker heartbeat.

Why is solving this problem impactful?

The high-priority request can not fail; otherwise, the cluster may refuse to serve.