Revert "Have AssetFileDescriptor.AutoCloseInputStream use pread"

Revert submission 20068774-b-168310122

Reason for revert: This caused b/263325931

Bug: b/263325931
Reverted changes: /q/submissionid:20068774-b-168310122
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f2ad1a434b34394a95c187e78998f2955d89efa5)
Merged-In: I3af382c65d9b230901ff15575e394bdcb4e953ef
Change-Id: I3af382c65d9b230901ff15575e394bdcb4e953ef