Revert "ANDROID: Incremental fs: Set credentials before reading/writing"

This reverts commit 28688d32.

Reason for revert: rolling the three fixes into one with feature flag
Bug: 174692664
Test: incfs_test passes
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Change-Id: I85cb75b7acb5606659698a6d0e0918ffb731009d