Proguard Google Play services: stop keeping entire package trees

BUG=272790

Change-Id: Ifd664f7656cd626551f1875b42a619a6034dac10
Reviewed-on: https://chromium-review.googlesource.com/295670
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Aurimas Liutikas <aurimas@chromium.org>
Commit-Queue: Aurimas Liutikas <aurimas@chromium.org>
Tested-by: Aurimas Liutikas <aurimas@chromium.org>