Remove flags for encrypted AVDTP & AVCTP channel

b/345258562 has received a month of soak and is ready for flag removal.
Ordinarily we would leave this until release, but it needs to be done
early in this case because flag removal is a requirement for Dr. No on
the associated security backports.

Test: mmm packages/modules/Bluetooth
Bug: 357662929
Bug: 315241296
Change-Id: I8d4ab527ba2546042553703157e2678bb5e6b803