Wifi: Maintain configKey generation logic same in all APIs

AutoJoinController uses configKey to distinguish networks. It compares
configKeys of saved network with recent ScanResult. WifiConfiguration
has two different APIs to generate configKey based on input variables.
Framework should use same logic to generate configkey even though input
differs. This fix ensures the parity between configKey(boolean) and
configKey(ScanResult) APIs.

Change-Id: I4d19b3ba37d784d1a73c53df33b52c3a427b60b9
CRs-Fixed: 806222