floss: Refactor TriggerUpdateConnectableMode

Now we can have the adapter object in the socket manager, which shall
make the scan mode update mechanism simpler.

Bug: 361510982
Tag: #floss
Test: mmm packages/modules/Bluetooth
Test: manual pair/unpair device, verify scan mode is correct
Test: manual turn on/off NearbyShare, verify scan mode is correct
Test: manual suspend/resume, verify scan mode is correct
Test: bluetooth_AdapterSRHealth.sr_while_powered_off.floss
Flag: EXEMPT, Floss-only changes
Change-Id: I82768549fb9ddff1027e698eb73dbc36a5750f01