remove the busy tone value from the KEY_DISCONNECT_CAUSE_PLAY_BUSYTONE_INT_ARRAY

The busy tone value should not be in the default disconnect cause array.
This can cause issues with the busy label as it can be overriden by
Telecom instead of the precise label passed by the lower layer

Bug: 296968778
Test: unit tests + manual
Change-Id: I10f72c6be279459bfd611fa1397149d122ec1d07