mysqlcluster: fix the bug about io hang xenon no switch leader #364

[acekingke]

What type of PR is this?

/enhancement

Which issue(s) this PR fixes?

Fixes #364

What this PR does?

Summary:

Special notes for your reviewer?

[runkecheng]

@qianfen2021

[runkecheng]

I use Chaos mesh to simulate IO delay, Leader does not switch

kind: IOChaos
apiVersion: chaos-mesh.org/v1alpha1
metadata:
  namespace: default
  name: io-delay
  annotations:
    experiment.chaos-mesh.org/pause: 'false'
spec:
  selector:
    namespaces:
      - default
    labelSelectors:
      role: LEADER
  mode: one
  action: latency
  delay: 60s
  percent: 100
  volumePath: /var/lib/mysql