Merge "Better error message for drop_caches_test" into main am: 4097ccc24e

Original change: https://android-review.googlesource.com/c/platform/test/vts-testcase/kernel/+/2904935

Change-Id: Ib6dc4092fb651b2463dc2d60cad8642c67387872
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>