Remove TEDCANID & TEDCNID

[georgiana-b]

Currently we store:

• Bid.xTEDCANID - the ID of contract award notice from TED
• Tender.xTEDCNID - the ID of the contract notice from TED

The point, if I remember well (please correct me @zufanka) - was to link to the original TED notice somewhere in the tender details.
However, we never actually used it and as it turns out it's buggy anyway. We currently just retrieve the sourceID of the first publication that has type CONTRACT_AWARD but there can be multiple of them from different sources. So the ID we retrieve now is not always from TED.

Either we make sure we only get the sourceID of publications from TED or we remove this field completely. I would argue for the latter because we will start storing the sourceURL (the URL of the original TED notice) anyway and that will make it super easy to point to the original.