billing: Add file size to request records

Request records submitted by doors lack the file size (they always
appeared as 0 in billing records). This patch adds the file size for
all protocols except for NFS.

Target: trunk
Request: 2.10
Request: 2.9
Request: 2.8
Request: 2.7
Request: 2.6
Require-notes: yes
Require-book: yes
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7360/
(cherry picked from commit ef3d069dd73275189543be30160ed29484e7c2ec)
Merge pull request #914 from gbehrmann/fix/2.6/rb7360

billing: Add file size to request records