do not "auto resume" for errors in dump unit

[csuzhangxc]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do? If possible, provide a recipe for reproducing the error.

   Run a task with "Couldn't acquire global lock"

2. What did you expect to see?

   the task keep paused

3. What did you see instead?

   still "auto resume".

   for errors in dump unit, most of them should not succeed after resumed, so no extra workload on upstream MySQL/MariaDB is better.

4. Versions of the cluster

   • DM version (run dmctl -V or dm-worker -V or dm-master -V):

     v1.0.6