UNIT TEST FAILURE: StringFamilyTest.MGetSet

```
/__w/dragonfly/dragonfly/src/server/string_family_test.cc:239: Failure
75: Expected: (ivec[1]) >= (ivec[0]), actual: 692 vs 693
....
[ FAILED ] StringFamilyTest.MGetSet (1228 ms)
```
Failed in epoll mode.

https://github.com/dragonflydb/dragonfly/actions/runs/26750654009/job/79052054829?pr=7426#step:9:19184

Note that it took 1230ms when in normal mode it's around 200ms.

it's the first time I see this test failing.

The failure is in src/server/string_family_test.cc:239, in StringFamilyTest.MGetSet. Start by reproducing it in epoll mode and compare it with normal mode, using the linked GitHub Actions run as the failure reference. Done means the test no longer fails spuriously in epoll mode and the timing behavior is understood.

Written by the indexing model from the issue text.