Floss: socket: Clean up RFCOMM connections when callback is remove

This patch refactored the structures so we can clean up the connecting
and listening sockets differently.

Bug: 296819230
Tag: #floss
Test: Restart AshChrome and make share the old RFCOMM server is closed
Test: Nearby Sharing files as sender/receiver
Test: mmm packages/modules/Bluetooth
Change-Id: I60f4bc03546a575d7b60346016f250a651af56f3