Always only use recording with most sources when single song matching

Acoustids often match to more than one recordings, these recordings may be

1. Same recording but incorrectly exists as multiple recordings in MusicBrainz
2. Different recording of same song
3. Different song

the NumOfSources is a good indicator of the best match but is not always correct however when only matching a single song we have less checks and balances than when matching a number of songs to a release so we should err on the side of caution and only consider the recording with the most sources even if this means that a few songs dont get matched when they could have been,