Revert^2 "Track Bitmap native allocations"

This reverts commit 4858b218.

Reason for revert: fixed the failed test case in b/368409430

In this CL, we used 'com.android.libcore.readonly.Flags.nativeMetrics()'
instead, this flag is forced-read-only which does not involve I/O, thus
preventing failures such as in "Isolated Process" where I/O permission
is disabled. See ag/29673659.

Change-Id: I03ef8dc09d9d668026752b49f196a081d7940626