login_processing.php: refactor duplicated code
login_processing.php: refactor duplicated code

A large chunk of the multi cookie processing was duplicated, so
we do it after the if-else statement.

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