Fix memory leak

Bug: 166073521
Test: atest VtsHalNeuralnetworksV1_2BenchmarkTestCases (with additional logging on model construction and destruction)
Test: atest VtsHalNeuralnetworksV1_3BenchmarkTestCases
Change-Id: I5bef5c04d1659a93f8dd1b3ad1c1c7a56fc5a9ea
Merged-In: I8885efc19a0846b4855cc6fa1a32820ebe41aab6
(cherry picked from commit 78819052d898cdfe77033dbe59e0839a092f80a9)
2 files changed