Bugfix: Fix IoScheduler::yield_until and improve tests

[willkill07]

Description

This PR simplifies the implementation of yield_for and yield_until while also eliminating a bug in yield_for which can cause it to prematurely notify.

Closes #532

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[willkill07]

/merge

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.00%. Comparing base (22409a5) to head (5ad7e3d).
Report is 1 commits behind head on branch-25.02.

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-25.02     #533      +/-   ##
================================================
- Coverage         74.03%   74.00%   -0.04%     
================================================
  Files               407      407              
  Lines             15103    15103              
  Branches           1198     1198              
================================================
- Hits              11182    11177       -5     
- Misses             3921     3926       +5     

Flag	Coverage Δ
cpp	70.65% <ø> (-0.04%)	⬇️
py	44.07% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cpp/mrc/src/public/coroutines/io_scheduler.cpp	65.19% <ø> (ø)

... and 4 files with indirect coverage changes

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