Remove tmp directory after CompilationCachingTest if cache not supported.

The tmp directory is only removed when the driver reports caching not
supported, otherwise it is kept for debugging purpose.

Test: 1.2 VTS tests with sample driver
Change-Id: I5969beb1ec365c992765f40d7693630606f16e18
Merged-In: I5969beb1ec365c992765f40d7693630606f16e18
(cherry picked from commit 350d91b1)