[Passpoint] Optimize loops that iterate on Providers

Optimize getWifiConfigsForPasspointProfiles, and
findBestMatchScanDetailForProviders: skip search loop
if the map of providers is empty.

Bug: 149517632
Test: atest PasspointManagerTest
Test: atest PasspointNetworkNominateHelperTest
Change-Id: I799483cf38b8df131514285855c97fc531e6eecd
2 files changed