perf(rust): Use AtomicWaker in async engine task joiner

[orlp]

We were waiting (potentially very long) on a locked mutex when awaiting our own executors tasks, use an atomic waker for the join instead.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 21 lines in your changes missing coverage. Please review.

Project coverage is 78.96%. Comparing base (52ea381) to head (4ce424e).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-stream/src/async_executor/task.rs	0.00%	21 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #20604   +/-   ##
=======================================
  Coverage   78.95%   78.96%           
=======================================
  Files        1564     1564           
  Lines      220882   220881    -1     
  Branches     2510     2510           
=======================================
+ Hits       174401   174415   +14     
+ Misses      45906    45891   -15     
  Partials      575      575           

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