Bugfix: Fix fragment name for Quota middleware

  Bugfix for commit 4157cb9 (uniformisation of pipeline names)
  According other swift proxy middlewares, the concat fragments
    doesn't contains « proxy » (concat frag. are generated by pipeline)
    see l195 and l196 of tests/site.pp

Change-Id: I99f9e5f5282b3e8db89fd56109ec8074ea1fa8f5