Consider priority to fix the Hot Region

[nolouch]

Feature Request

Describe your feature request related problem

In some situations, the hot region operator may fail, such as add a learner then timeout. Hot Region will not schedule the region again because the region is unhealthy with an unexpected peer number. but the region may always not fix in a long time, which lead the hot issues.

Describe the feature you'd like

• Consider priority to fix the Hot Region
• Figure out some reason about the long unhealthy status.

Describe alternatives you've considered

The hot region schedule needs to consider the unhealthy region.

Teachability, Documentation, Adoption, Migration Strategy

• GO