* Avoid the use of `runBlocking` inside coroutines. Schedule all
  coroutines below the test engine layer via regular dispatchers,
  bringing the test environment more in line with actual production
  environments.

* Remove direct use of Java's `Executors`, delegating to
  kotlinx.coroutines-provided dispatchers instead.

* Preserve coroutine context (which includes lots of Kotest
  configuration) in multithreaded test executions.

* Remove hard-coded 1-day time limit for multithreaded test executions.

* Change tests relying on single-threading from a coroutine model to a
  thread model, removing coroutine invocations (`delay`), replacing
  those with thread invocations (`Thread.sleep`).

* Avoid leaking threads by closing dispatchers after use.

* Keep the `assertionCounter` synchronized with thread-switching
  coroutines.

* Remove `fun <K, V> concurrentHashMap(): MutableMap<K, V>`, which was
  not thread-safe.

* Make `FixedThreadCoroutineDispatcherFactory.dispatcherAffinity`
  thread-safe.

* Revert a change in `ConcurrentTestSuiteScheduler.schedule` by
  commit c316bbd, which replaced
  `launch` with `async` plus `joinAll`. This was functionally
  equivalent, but `async` was not needed, as there were no values
  returned, and `joinAll` was already performed by the enclosing
  `coroutineScope`.

# Conflicts:
#	kotest-extensions/kotest-extensions-blockhound/src/jvmTest/kotlin/io/kotest/extensions/blockhound/BlockHoundTest.kt

This avoids missing captured output.

Increase the minimum delay to 50 milliseconds based on observed
behavior.