Split bta_dm_execute_queued_request to search and discovery

State machines are separate, should handle queuing separately

Bug: 330675788
Bug: 335732980
Flag: com.android.bluetooth.flags.separate_service_and_device_discovery
Test: mma -j32
Change-Id: Ib6bfa989ef71d29924524d1ef4f7ddb1e2d6280b