add a flag for ConnectionServiceFocusManager#getCurrentFocusCall

A flag should have been added with the changes in b/280128990.  Gating the changed code with a flag to ensure the code has enough soak time before release.

Fixes: 309541253
Bug:  280128990 (original bug)
Test: build + existing tests
Change-Id: Ibb19b05f5005e885fe5dde690f74ad37f7d062d7
4 files changed