High IOWAIT usage

[Jeglerjeg]

Describe the bug
While dragonfly is running, all free CPU time is used as IOWAIT even when idle and with no keys stored

To Reproduce
Steps to reproduce the behavior:

1. Run dragonflydb
2. Check CPU usage through a tool like top
3. See high IOWAIT

Expected behavior
IOWAIT is only consumed when IO operations happen.

Environment (please complete the following information):

 - OS: Debian 12.2
 - Kernel: 6.1.0-13-arm64 #1 SMP Debian 6.1.55-1 (2023-09-29) aarch64 GNU/Linux
 - Containerized?: Docker
 - Dragonfly Version: 1.12.1

[romange]

Seems that it's caused by iouring API treating pending io requets as iowait even for networking. therefore it's a behavior change on kernel side. See axboe/liburing#943 for more info.