Remove unused method from CarrierTextManager

CarrierTextManager#getCarrierHelpTextForSimState
is not used any more, so remove it.

As CarrierTextManager#getCarrierHelpTextForSimState
is removed, related strings are also not used any more,
so this patch also removes related strings definitions.

Cherry-picked from Ie09e492494429207bd2a1c6a12b58fa76c8e47ea

Bug: 305059658
Test: Build pass
Change-Id: Ib353825b79c63b93ea08cb8d19aab1ca0d86e62d
Signed-off-by: Wei Huang <hwbest.v@gmail.com>
Signed-off-by: Honggang Luo <luo.loky@gmail.com>
Signed-off-by: Chao Yuan <chaoyuanx@gmail.com>