Fix the system crash issue when secondary user clicks any 802.1x AP on

Wifi Picker.

Catch the exception when keystore failed to list the certs

Bug: 73794111
Test: test it with clicking the Google-A on Wifi Picker.
Test: make ROBOTEST_FILTER="(WifiConfigControllerTest)"
RunSettingsRoboTests -j32
RunSettingsRoboTests: OK (12 tests)

Change-Id: I0db66730261c72ef35d1b299bacd2aed7710d247