Re-enable DnsCacheTest as it miraculously works again

app/src/androidTest/java/org/fdroid/download/DnsCacheTest.kt

@@ -9,7 +9,6 @@ import kotlin.test.assertNotNull
 import kotlin.test.assertNull
 import kotlin.test.assertTrue
 import org.fdroid.settings.SettingsManager
-import org.junit.Ignore
 import org.junit.Test
 import org.junit.runner.RunWith
 
@@ -82,7 +81,6 @@ class DnsCacheTest {
   }
 
   @Test
-  @Ignore("failing") // TODO
   fun preloadCacheTest() {
     // test setup
     settings.useDnsCache = true