The `round()` returning floating point number is not a good idea. This is due to floating point
representation is imprecise and sometimes it cannot faithfully represent a number, for example
`0.09 + 0.01 !== 0.1 `. Therefore, it should be avoided and/or utilize other function
to achieve the goal.
Also, improve `window.qBittorrent.Misc.toFixedPointString()` and add test cases.
PR #22281.
