LeAudio: Refactor unicast stream parameters update

Aligns two very similar data structures to a single data type in order
to remove complexity and redundant copying.
There is no behavioral change, just the data types were refactored.

Bug: 388733112
Test: atest --host bluetooth-test-audio-hal-le-audio-software bluetooth-test-audio-hal-aidl-leaudio-utils bluetooth_le_audio_test bluetooth_le_audio_client_test  bluetooth_test_broadcaster bluetooth_test_broadcaster_state_machine bluetooth_le_audio_codec_manager_test net_test_btif net_test_btif_hh net_test_btif_stack
Flag: EXEMPT; No functional change, regressions covered with unit test
Change-Id: I239110556f2ee52f4956cfdfbf3fa882f7f2d8d0