Ignore CoroutineSchedulerStressTest.testExternalTasksSubmission

It is not reliable. See #904

Author: elizarov

core/kotlinx-coroutines-core/test/scheduling/CoroutineSchedulerStressTest.kt

@@ -8,6 +8,7 @@ import kotlinx.coroutines.*
 import kotlinx.coroutines.internal.*
 import kotlinx.coroutines.scheduling.SchedulerTestBase.Companion.checkPoolThreadsCreated
 import org.junit.*
+import org.junit.Ignore
 import org.junit.Test
 import java.util.concurrent.*
 import java.util.concurrent.atomic.*
@@ -37,6 +38,7 @@ class CoroutineSchedulerStressTest : TestBase() {
 
     @Test
     @Suppress("DEPRECATION")
+    @Ignore // this test often fails on windows, todo: figure out how to fix it. See issue #904
     fun testExternalTasksSubmission() {
         stressTest(CommonPool)
     }