Drop connection when atttempting to disable encryption

Pixel devices in the field appear not to drop the connection or
reestablish encryption after receiving a command to disable link
layer encryption on an encrypted link, a certification
requirement.  Add a check forcing connections to drop in this case.

Bug: 251436534
Test: atest: bluetooth, lab validation forthcoming
Tag: #security
Ignore-AOSP-First: Security
Change-Id: Ie9d69be65fa1163c1ee10ca19153e98e737743cb