Add missing method NativeAllocationRegistry.createMalloced(Class,long)

Method NativeAllocationRegistry.createMalloced(Class, long) was missing
in Ravenwood libcore-fake. ag/34933001 failed ravenwood test because of
this, see b/441804951.

This CL added the missing method.

Bug: b/441804951
Flag: EXEMPT bugfix
Test: submit ravenwood test with ag/34933001 which revealed the bug
Change-Id: Idb95db2fdfc974841f850b8e38f64cc720a1bd44