srm: Cancel upload path if request was aborted

If the request is aborted while pnfs manager creates the
unique upload path, the SRM would fail to release the
upload path.

This patch fixes this problem.

Target: trunk
Require-notes: yes
Require-book: no
Request: 2.9
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7077