fix the second call of make_task

[wanghan-iapcm]

should clear the existing task and make new ones

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (fe86aef) 88.09% compared to head (d5a9dcb) 88.09%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #159 +/- ## ======================================= Coverage 88.09% 88.09% ======================================= Files 80 80 Lines 4007 4008 +1 ======================================= + Hits 3530 3531 +1 Misses 477 477 ``` | [Files Changed](https://app.codecov.io/gh/deepmodeling/dpgen2/pull/159?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=deepmodeling) | Coverage Δ | | |---|---|---| | [dpgen2/entrypoint/common.py](https://app.codecov.io/gh/deepmodeling/dpgen2/pull/159?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=deepmodeling#diff-ZHBnZW4yL2VudHJ5cG9pbnQvY29tbW9uLnB5) | `75.67% <100.00%> (ø)` | | | [...oration/task/customized\_lmp\_template\_task\_group.py](https://app.codecov.io/gh/deepmodeling/dpgen2/pull/159?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=deepmodeling#diff-ZHBnZW4yL2V4cGxvcmF0aW9uL3Rhc2svY3VzdG9taXplZF9sbXBfdGVtcGxhdGVfdGFza19ncm91cC5weQ==) | `95.29% <100.00%> (+0.05%)` | :arrow_up: |

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