Audio Policy Manager: fix priority of routing strategies

The priority ordered list of routing strategies in the default
engine was modified unintentionally by commit ad3dce95.
This CL restores the order by redefining the legacy strategies
enum values in the desired order.

Flag: EXEMPT bug fix
Test: repro steps in bug
Bug: 371082808
Change-Id: I4355603dcab7034f59a8f4e7796d5823ad14646c