[mlir] Async: re-enable tests after fixing fkakines

Test flakiness was fixed by: https://github.com/llvm/llvm-project/commit/9edcedf7f222ce7c893d1e3bf19b3a7a1f0f2218

Runs these tests to verify that all parts of the lowering work correctly.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D93384