Fix audio control device to context test

Added a fix to check if the audio device repeats since the original
change did not correctly add the context to the already set volume
group contexts list.

Bug: 359686069
Test: atest VtsAidlHalAudioControlTest
Flag: EXEMPT HAL interface
Change-Id: Iee3751349d6609c93e383c2b83fc8525e8335cac