fix: round the timeout up instead of rounding it down

[romange]

Fixes https://github.com/dragonflydb/dragonfly/issues/2014

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (e0987ee) 77.34% compared to head (bcad224) 77.40%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #157 +/- ## ========================================== + Coverage 77.34% 77.40% +0.05% ========================================== Files 98 98 Lines 7173 7173 ========================================== + Hits 5548 5552 +4 + Misses 1625 1621 -4 ``` | [Files](https://app.codecov.io/gh/romange/helio/pull/157?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Roman+Gershman) | Coverage Δ | | |---|---|---| | [util/fibers/epoll\_proactor.cc](https://app.codecov.io/gh/romange/helio/pull/157?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Roman+Gershman#diff-dXRpbC9maWJlcnMvZXBvbGxfcHJvYWN0b3IuY2M=) | `87.73% <100.00%> (-1.42%)` | :arrow_down: | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/romange/helio/pull/157/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Roman+Gershman)

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