fix: remove sync_generator_adapter

[sjinks]

sync_generator_adapter was a mistake due to my misunderstanding of eager coroutines.

I thought an eager coroutine was completed synchronously from the caller's perspective and returned control to the caller when it was done. That was not true. An eager coroutine returns at the first suspending co_await.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.66%. Comparing base (b249844) to head (82ceffd).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #22      +/-   ##
==========================================
+ Coverage   84.56%   86.66%   +2.10%     
==========================================
  Files           6        5       -1     
  Lines         285      270      -15     
  Branches       54       53       -1     
==========================================
- Hits          241      234       -7     
  Misses          1        1              
+ Partials       43       35       -8     

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[github-actions]

Test Results

  5 files    5 suites   1m 1s ⏱️
 71 tests  71 ✅ 0 💤 0 ❌
355 runs  355 ✅ 0 💤 0 ❌

Results for commit 82ceffd.