add tear down to fix resources leak.

plugins/gradle/testSources/org/jetbrains/plugins/gradle/service/task/GradleTaskManagerTest.kt

@@ -15,6 +15,7 @@ import org.jetbrains.plugins.gradle.settings.DistributionType
 import org.jetbrains.plugins.gradle.settings.GradleExecutionSettings
 import org.jetbrains.plugins.gradle.tooling.builder.AbstractModelBuilderTest
 import org.jetbrains.plugins.gradle.util.GradleConstants
+import org.junit.After
 import org.junit.Before
 import org.junit.Test
 
@@ -42,6 +43,15 @@ class GradleTaskManagerTest: UsefulTestCase() {
                                                      DistributionType.WRAPPED, false)
   }
 
+  @After
+  override fun tearDown() {
+    try {
+      myTestFixture.tearDown()
+    } finally {
+      super.tearDown()
+    }
+  }
+
   @Test
   fun `test task manager uses wrapper task when configured`() {