change the default value in [target-check-tables] (sync-diff-inspector)

[KASSADAR]

In the peripheral components of TiDB, the default value of the filter is usually ['.', '!mysql.*', etc].
but in sync-diff-inspector, you should explicitly state what to do.
This results in the fact that under the default configuration, sync-diff-inspector does nothing, unlike other tools that do everything by default.