OtaDexopt: Fix after-ota space measure

Actually measure the available space.

Bug: 31458900
Change-Id: I16ecee6c275229bc21e908b88b24152484025bc8

services/core/java/com/android/server/pm/OtaDexoptService.java

@@ -172,6 +172,7 @@ public class OtaDexoptService extends IOtaDexopt.Stub {
             Log.i(TAG, "Cleaning up OTA Dexopt state.");
         }
         mDexoptCommands = null;
+        availableSpaceAfterDexopt = getAvailableSpace();
 
         performMetricsLogging();
     }