more robust autopopup concurrency test

java/java-tests/testSrc/com/intellij/codeInsight/completion/JavaAutoPopupTest.groovy

@@ -315,6 +315,8 @@ class JavaAutoPopupTest extends CompletionAutoPopupTestCase {
         tooQuick = lookup == null
         myFixture.type 'IO'
       }
+      joinAlarm() //I
+      joinAlarm() //O
       joinCompletion()
       assert lookup
       assert 'ArrayIndexOutOfBoundsException' in myFixture.lookupElementStrings