le_audio: Replace temporary context policy with direction for group

Patch replaces temporary context policy with group direction for LE
Audio devices.

Bug: 238143026
Tag: #feature
Test: atest BluetoothInstrumentationTests
Merged-In: Id36312ac3cb9743a6409a358564fcd93ac3655bb
Change-Id: Id36312ac3cb9743a6409a358564fcd93ac3655bb
(cherry picked from commit 0b6a4a66)