1105 (HY000): cannot set read timestamp to a future time

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

I'm running `v7.1.1` on K8s using the provided operator.

I configure read replicas like this to enable local reads:

```
mysql \
--host basic-tidb.tidb-cluster.svc.cluster.local \
--port 4000 \
--user root \
--password= \
--execute "set global tidb_replica_read = 'closest-replicas';"
```

I execute select statements which end with the following string to enable stale reads:

```
AS OF TIMESTAMP TIDB_BOUNDED_STALENESS(NOW() - INTERVAL 60 SECOND, NOW())
```

### 3. What did you see instead (Required)

My reads sometimes fail with the error `1105 (HY000): cannot set read timestamp to a future time`.
Also, this typically happens on just one of my three physical nodes - perhaps that node has a clock skew issue which is surfacing this bug.

Note, this only started to happen when I upgraded to `v7.1.1` from `v6.5.2`.
I don't believe my code changed in any important way in the interim.