row level checksum calculation failed on timestamp value

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Bug Report

Please answer these questions before submitting your issue. Thanks!

ref pingcap/tiflow#10573

1. Minimal reproduce step (Required)

set global tidb_enable_row_level_checksum=true;

set @@global.time_zone = '-05:00'

create table t (a int primary key, b timestamp);

insert into t values (1, '2023-02-09 13:00:00');

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

When calculating checksum for timestamp value, should convert it to UTC, and then perform the calculation, to make the checksum value irrelevant to the time zone.

3. What did you see instead (Required)

Calculate checksum for the timestamp value based on time zone, this makes the downstream TiCDC changefeed verify changefeed failed, if the TiCDC server time zone is not the same as the TiDB.

4. What is your TiDB version? (Required)

master