dumpstate: Remove wpa_cli usage

List of saved networks is dumped out by WifiConfigManager during
bugreport collection. The 'wpa_cli` command in dumpstate.cpp is
non-functional since the saved networks are no longer saved in
wpa_supplicant.

Bug: 62068865
Test: Collected bugreport and ensured that there are no wpa_cli errors.
Change-Id: I0080bf10dafcbd187fcf583232ce64dd3868d818