[SB] Remove "phone" from call chip content description.

Apps that trigger the call chip may not necessarily be making *phone*
calls, so remove it from the content description.

Bug: 364653005
Flag: EXEMPT bugfix
Test: Trigger call chip -> verify content description is "Ongoing call"
plus the timer amount

Change-Id: I7de89c98bc89d0fe38cc171af8b9ed7d30dd7235