Sequencing center grabs user center

[saramonzon]

We used to use Sequencing center field in Service table as the center were sequencing was done. Now this field is filled with the center were the requesting user belongs.

As the sequencing center now is recorded in the sample, we have to change this field to "service center" so it is filled with the center where the user belongs in the moment when they request the service. This way we can use that field here:
https://github.com/BU-ISCIII/iSkyLIMS/blob/73f54922e48db208b7ba1c4be3892bdbb6480356/iSkyLIMS_drylab/utils/drylab_common_functions.py#L102-L126

So we don't have weird behaviour if a user changes it's center adscription.