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
(cherry picked from commit 15fa2eee32566e46907f60135e7df19f449854c9)
Merge pull request #659 from gbehrmann/fix/2.9/rb7077

Fix/2.9/rb7077