fix(arm): grow slice not clear mem

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 47.82609% with 12 lines in your changes missing coverage. Please review.

Project coverage is 52.63%. Comparing base (125ff79) to head (d347689).

Files	Patch %	Lines
internal/rt/stubs.go	47.36%	7 Missing and 3 partials :warning:
internal/rt/growslice.go	50.00%	1 Missing and 1 partial :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #674 +/- ## ========================================== - Coverage 52.85% 52.63% -0.23% ========================================== Files 174 142 -32 Lines 11470 11397 -73 ========================================== - Hits 6063 5999 -64 + Misses 5071 5068 -3 + Partials 336 330 -6 ```

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