Deal with async generator throughput issue

[adityarao2005]

The test case GeneratorTestSuite.TestAsyncGeneratorThroughput fails when the

This test was failing with C++20 coroutines due to stack overflow even with symmetric transfer enabled for large iterations. As of right now, this test uses a reduced count (40,000) to avoid stack overflow issues
that occur with C++20 coroutines when processing >45,000 individual items thus passes for 40,000 iterations but fails for >45,000 iterations.

[adityarao2005]

Temporary workaround: use the batched processing approach shown in GeneratorTestSuite.TestAsyncGeneratorBatchedProcessing.