Remove some broken tests (#3513)

These tests haven't been reliable for a very long time for some
reason. We could ensure that they pass by a manual check, but it
feels like nobody actually relies on this behavior, and it's not
clear who would even want to.

Author: dkhalanskyjb

kotlinx-coroutines-test/common/test/RunTestTest.kt

@@ -69,20 +69,6 @@ class RunTestTest {
         deferred.await()
     }
 
-    /** Tests that a dispatch timeout of `0` will fail the test if there are some dispatches outside the scheduler. */
-    @Test
-    fun testRunTestWithZeroTimeoutWithUncontrolledDispatches() = testResultMap({ fn ->
-        assertFailsWith<UncompletedCoroutinesError> { fn() }
-    }) {
-        runTest(dispatchTimeoutMs = 0) {
-            withContext(Dispatchers.Default) {
-                delay(10)
-                3
-            }
-            fail("shouldn't be reached")
-        }
-    }
-
     /** Tests that too low of a dispatch timeout causes crashes. */
     @Test
     fun testRunTestWithSmallTimeout() = testResultMap({ fn ->

kotlinx-coroutines-test/jvm/test/migration/RunTestLegacyScopeTest.kt

@@ -66,19 +66,6 @@ class RunTestLegacyScopeTest {
         deferred.await()
     }
 
-    @Test
-    fun testRunTestWithZeroTimeoutWithUncontrolledDispatches() = testResultMap({ fn ->
-        assertFailsWith<UncompletedCoroutinesError> { fn() }
-    }) {
-        runTestWithLegacyScope(dispatchTimeoutMs = 0) {
-            withContext(Dispatchers.Default) {
-                delay(10)
-                3
-            }
-            fail("shouldn't be reached")
-        }
-    }
-
     @Test
     fun testRunTestWithSmallTimeout() = testResultMap({ fn ->
         assertFailsWith<UncompletedCoroutinesError> { fn() }