This test needs to run on 3.8 kernel.
It seems to be "not applicable" to all the models in the lab: https://stainless.corp.google.com/search?test=^kernel\_Bootcache%24&exclude_non_release=true&exclude_cts=true&col=build&row=board_model&view=matrix&first_date=2019-01-12&last_date=2019-01-18

Ask: Remove the test from the kernel_per-build_regression suite, and delete the test itself from our sources.