When using device build info do not clean up tests dir

When using the option --use-device-build-info, the tests
dir of the build is populated, do not delete it as part
of cleanUp() step otherwise we might delete testcases/

Test: unit tests
./cts-tradefed run cts-suite -m CtsGesture --use-device-build-info
Bug: 65546277

Change-Id: I818adeff7c97511097bcf8daed84f5d7e90c923b
2 files changed