CheckStoreHealth does not work wtih TiFlash

[shiyuhang0]

Bug Report

1. Describe the bug

The checkStoreHealth method in StoreHealthyChecker will check the status of the store periodically.

However, the check for TiFlash always fails and returns false because TiFlash does not provide the grpc health checking service. See here for more details about GRPC Health Checking Protocol

Thus, the status of TiFlash will always be unreachable.

2. Minimal reproduce step (Required)

3. What did you see instead (Required)

4. What did you expect to see? (Required)

5. What are your Java Client and TiKV versions? (Required)

• Client Java: <= 3..3.4
• TiKV: any version