Test `trim on SET with big value` (introduced from #11817) fails under mac m1 with libc mem_allocator.
The reason is that malloc(33000) will allocate 65536 bytes(>42000).
This test still passes under ubuntu with libc mem_allocator.
```
*** [err]: trim on SET with big value in tests/unit/type/string.tcl
Expected [r memory usage key] < 42000 (context: type source line 471 file /Users/iospack/data/redis_fork/tests/unit/type/string.tcl cmd {assert {[r memory usage key] < 42000}} proc ::test)
```
simple test under mac m1 with libc mem_allocator:
```c
void *p = zmalloc(33000);
printf("malloc size: %zu\n", zmalloc_size(p));
# output
malloc size: 65536
```
(cherry picked from commit 3fba3ccd96)
(cherry picked from commit 646069a900)
89391e42c8