libmeminfo_test: Use vendor api level in the tests ro.vendor.api_level property is provided for tests to check for the API level supported by the device. Use it instead of the first_api_level. Bug: 203839958 Signed-off-by: Suren Baghdasaryan <surenb@google.com> Change-Id: I9338ab122d72b9f7011245a566318a500c20e878