fix: temporarily disable testConcurrentRequests because of flakiness (#1487)

Author: 0marperez

runtime/protocol/http-client-engines/test-suite/common/test/aws/smithy/kotlin/runtime/http/test/AsyncStressTest.kt

@@ -17,6 +17,7 @@ import kotlin.time.Duration.Companion.milliseconds
 class AsyncStressTest : AbstractEngineTest() {
 
     @Test
+    @Ignore // FIXME re-enable this test after debugging why it's so flaky, particularly on Mac OS (JVM)
     fun testConcurrentRequests() = testEngines {
         // https://github.com/awslabs/aws-sdk-kotlin/issues/170
         concurrency = 1_000