TestInstallRelease_Wait_Interrupted and
TestInstallRelease_RollbackOnFailure_Interrupted assert that the detached
installation goroutine has exited by sleeping a fixed 10s -- exactly the
FailingKubeClient WaitDuration the goroutine blocks on. Sleeping the same
duration the goroutine takes is a zero-margin race: if the goroutine
finishes a hair after the fixed sleep elapses (scheduler jitter under load),
getGoroutineCount() has not decremented yet and the assertion flakes.
Replace the fixed sleep + point-in-time assert with is.Eventually polling
getGoroutineCount() (30s ceiling, 10ms tick). It returns as soon as the
goroutine has actually finished and no longer races the exact wait
duration. Test-only; no change to install behavior.
Signed-off-by: Nikolaus Schuetz <nikolauspschuetz@gmail.com>