By Abigail Summerville and Matt Tracy (Reuters) – Wall Street banks completed the sale of $8.55 billion in loans and bonds backing the leveraged buyout of business software company Citrix Systems Inc by accepting a $700 million loss, a person familiar with the matter said on Wednesday. The process emerged as a key test of banks’ ability to offload junk-rated debt from their books, a process that is necessary for them to recycle capital and comply with regulations governing their financial health. While the syndication was completed successfully, it was done at a steep discount to the levels th…