fix: fix vue2 array reactive bug

[yiyunwan]

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What have you changed?

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (d6f827c) 99.55% compared to head (5ce9a86) 99.55%. Report is 1 commits behind head on formily_next.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## formily_next #4042 +/- ## ============================================= Coverage 99.55% 99.55% ============================================= Files 152 152 Lines 6717 6720 +3 Branches 1821 1822 +1 ============================================= + Hits 6687 6690 +3 Misses 30 30 ```

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