floss: Trigger OnDisconnection during suspend

When suspending, we do ACL disconnection of all devices. Depending on
the firmware implementation, the actual HCI Disconnection event can be
emitted immediately afterwards or after the link layer disconnects. To
speed up suspend, we will mask out the HCI Disconnection event and
simply run the `OnDisconnection` method right away.

Bug: 231435700
Tag: #floss
Test: Manual test on ChromeOS
Change-Id: If74b15562e224850aeac02a22e5a24b4d25a9a88