Unselect track to not affect next selected track

Bug: 34152189

Change-Id: Ic8eae5a800db96cea6a1763382c55f80a4746f94
Test: android.security.cts.StagefrightTest#testStagefright_bug_25812590
diff --git a/tests/tests/security/src/android/security/cts/StagefrightTest.java b/tests/tests/security/src/android/security/cts/StagefrightTest.java
index 8f4b5d9..28edcc1 100644
--- a/tests/tests/security/src/android/security/cts/StagefrightTest.java
+++ b/tests/tests/security/src/android/security/cts/StagefrightTest.java
@@ -447,6 +447,7 @@
                     codec.release();
                 }
             }
+            ex.unselectTrack(t);
         }
         ex.release();
         String cve = rname.replace("_", "-").toUpperCase();