[Invisalign2] Make BTA_DmBleConfigLocalPrivacy synchronous

BTA_DmBleConfigLocalPrivacy is currently implemented
as asynchronous by posting a task to main thread.

With BTA_DmAddBleKey being made synchronous, this one
should be made synchronous, otherwise, IRKs of
bonded BLE devices won't be loaded properly if
BTA_DmAddBleKey is called before local privacy
is properly initialized, as reported in b/315736888.

Bug: 315736888
Bug: 311196228
Bug: 301661850

Test: atest net_test_btif_stack
Test: pair with a BLE device, restart Bluetooth and connec
Change-Id: Idc80e068767f2bb67450145fce3e0e3c8a2c45a5