remove API RoleManager.getFinancialSms

getFinancialSms is not functional and not used today, thus
remove it to avoid future confusion

Bug: 138745655
Bug: 140908357
Test: atest android.telephony.cts.SmsManagerTest
Change-Id: Ib57d0fc189b6c894227894ee02b592f7ee46f22f
(cherry picked from commit d6b26731)
Merged-in: Ib57d0fc189b6c894227894ee02b592f7ee46f22f