Audio VTS: run tear-down hooks in LIFO instead of FIFO

The audio tests use a static cache of some HAL objects for
performance reasons (speed up by 10x on Pixel).
Those object are destroy during the test environment tear-down.

This tear-down was destroying the objects in a FIFO instead of LIFO
order. Thus the DeficesFactory was destroyed before the Device it
created.

Bug: 79889318
Test: vts-tradefed run commandAndExit vts --module VtsHalAudioV2_0Target
      check that the device destructor is called before the
      devicesFactory one.
Change-Id: I1b4345158139ba14a8779a9508f7ebdc41129d1d
Merged-In: I1b4345158139ba14a8779a9508f7ebdc41129d1d
Signed-off-by: Kevin Rocard <krocard@google.com>

audio/2.0/vts/functional/AudioPrimaryHidlHalTest.cpp

@@ -124,7 +124,7 @@ class Environment : public ::testing::Environment {
    public:
     using TearDownFunc = std::function<void()>;
     void registerTearDown(TearDownFunc&& tearDown) {
-        tearDowns.push_back(std::move(tearDown));
+        tearDowns.push_front(std::move(tearDown));
     }
 
    private: