Remove unneeded scripts for d8, r8-compat-proguard and retrace. am: 67a7974261 am: 6e2607fe3f

Original change: https://android-review.googlesource.com/c/platform/prebuilts/r8/+/2056145

Change-Id: I379609f0502923f964676731e3ab14eaf6645651
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>