Add region missing related diagnostic logs

## Requirement
Today when TiKV is doing rolling upgrade, TiDB may experience region missing error and has to back off the requests.
This is not expected because the rolling upgrade will do one TiKV per time and do evict leader before the restart. So theoretically the whole process should not impact user traffic.

To know why it happens, it needs to track how a specific region is invalidated in PD side. So more diagnostics logs are needed when invalidating a region.

### What did you do?

### What did you expect to see?
When region missing error occurred, we can search the region id in PD log and find when and why it's invalidated.
### What did you see instead?
No related log can be found at all.

### What version of PD are you using (`pd-server -V`)?
nightly.