Remove @hide for CarrierConfigManager constants

Remove @hide for CarrierConfigManager constants used outside of
Telephony mainline

referencing packages:
cts/tests
frameworks/base/packages/CarrierDefaultApp
frameworks/base/packages/SystemUI
frameworks/base/packages/Tethering
frameworks/base/services
frameworks/base/telecomm
frameworks/opt/wifi
packages/apps/Dialer
packages/apps/Settings
packages/providers/BlockedNumberProvider
packages/services/Car
packages/services/Telecomm
prebuilts/sdk

Test: build
Bug: 147447171
Change-Id: Ib3d8d904a80f11247012b01aceb92eaee2c84d5b