Remove unused strings from sysui

status_bar_settings_signal_meter_wifi_nossid
and
status_bar_settings_signal_meter_disconnected

Are no longer used as of what looks like L, and the latter string had an
errant capitalized "Internet" which is silly.

Test: it compiles?
Change-Id: I7b53994d85808743264fef7500d12ef4b3b69954
Fixes: 69389014