Revert "Allocate dex cache arrays at startup." am: cc97f11fe6

Original change: https://android-review.googlesource.com/c/platform/art/+/2270747

Change-Id: I40b5651ab0c5a21133339ad5134a26b14ab57c29
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>