preferences_processing.php: fix strict type error
preferences_processing.php: fix strict type error

The player ID is an int, not a string, so it should be escaped in
database queries with `escapeNumber`.

hemberger/smr,smrealms/smr,smrealms/smr,smrealms/smr,hemberger/smr,hemberger/smr,hemberger/smr